SNP MPs will vote against Boris Johnson's Brexit deal when it comes before the Commons, Westminster leader Ian Blackford revealed as he branded it a "disaster for Scotland".
He said the agreement, which was finally reached with the European Union on December 24, was an "unforgiveable act of economic vandalism and gross stupidity".
SNP leader and Scotland's First Minister Nicola Sturgeon has already accused the Conservatives of having "sold out Scottish fishing all over again" in the Brexit treaty.
But Alister Jack, the Scottish Secretary, insisted it would deliver for all parts of the UK, as he urged all MPs from north of the border to "give it their wholehearted support".
Mr Jack made the plea after the SNP Westminster leader said the agreement – which was published in full on Boxing Day – was a "very bad deal for Scotland".
It will come into force after the UK's current transition period, as it exits the EU, comes to an end on December 31.
MPs in the House of Commons will vote on the agreement on Wednesday December 30, with Mr Blackford saying: "Boris Johnson's extreme Tory Brexit is an unforgivable act of economic vandalism and gross stupidity, which will cause lasting damage to the economy and leave the UK much worse off at the worst possible time – during a pandemic and economic recession."
The Scottish Government has estimated the Brexit deal that has been agreed could cost Scotland's economy more than £9 billion by 2030, compared to staying in the EU, with the forecast 6.1% drop in GDP the equivalent to losing the equivalent of £1,600 per person.
Mr Blackford hit out: "Scotland has been completely ignored by Westminster throughout the Brexit process and we are being forced to pay a devastating price.
"It is clear that the only way to protect Scotland's interests, and regain the full benefits of EU membership, is to become an independent country.
"This is a very bad deal for Scotland, which will terminate our membership of the EU, rip us out of the world's largest single market and customs union, end our freedom of movement rights, and impose mountains of red tape, added costs and barriers to trade for Scottish businesses.
"The blame lies squarely with the Tory government."
Brexit trade deal done
Brexit trade deal done
EU Chief Negotiator for Brexit Michel Barnier (L) is watched by a Greek representative, while carrying a folder containing the 2000 page 'Brexit Trade Deal' as he arrives ahead of a special meeting of The Committee of the Permanent Representatives of the Governments of the Member States to the European Union (Coreper) at the European Council in Brussels on December 25, 2020. (Photo by Olivier HOSLET / POOL / AFP) (Photo by OLIVIER HOSLET/POOL/AFP via Getty Images)
In this picture taken on December 25, 2020 flags of the European Union can be seen fluttering outside the European commission headquarters in Brussels. (Photo by François WALSCHAERTS / AFP) (Photo by FRANCOIS WALSCHAERTS/AFP via Getty Images)
Trucks arrive via the Channel Tunnel at the port of Calais on December 25, 2020, after drivers underwent Covid-19 tests in England, where they were held since France closed borders with the UK in a bid to stop the spread of a new coronavirus strain. - Rail and sea links between the UK and France will remain open over Christmas to clear the backlog of thousands of trucks stranded by border closures due to the discovery of a new strain of coronavirus, Britain said on December 24, 2020. (Photo by FRANCOIS LO PRESTI / AFP) (Photo by FRANCOIS LO PRESTI/AFP via Getty Images)
LONDON, ENGLAND - DECEMBER 24: Prime Minister, Boris Johnson holds a press conference on reaching a Brexit trade deal in Downing Street on December 24, 2020 in London, England. Four and a half years after British voters elected to leave the EU, and mere days before the latest and presumably final deadline, UK and EU leaders have announced a trade deal defining the terms of the breakup. (Photo by Paul Grover - WPA Pool/Getty Images)
BRUSSELS, BELGIUM - DECEMBER 24: European Commission President Ursula von der Leyen (R) and European Union chief Brexit negotiator Michel Barnier (L) hold a joint press conference in Brussels, Belgium on December 24, 2020. The UK and EU reached a post-Brexit trade agreement on Christmas Eve on Thursday after four-and-a-half years of bitter negotiations and only a week to spare until the end of the transition period on Dec. 31. (Photo by Dursun Aydemir/Anadolu Agency via Getty Images)
LONDON, ENGLAND - DECEMBER 24: Journalists wait outside number 10 Downing Street as Prime Minister, Boris Johnson holds a press conference on reaching a Brexit trade deal on December 24, 2020 in London, England. Four and a half years after British voters elected to leave the EU, and mere days before the latest and presumably final deadline, UK and EU leaders have announced a trade deal defining the terms of the breakup. (Photo by Chris J Ratcliffe/Getty Images)
The media gathered outside 10 Downing Street, London, ahead of a briefing from Prime Minister Boris Johnson the agreement of a post-Brexit trade deal. (Photo by Victoria Jones/PA Images via Getty Images)
Police officers speak to an anti-Brexit protester at the gates of Downing Street, London. The UK and European Union are on the threshold of striking a post-Brexit trade deal. An announcement is expected on Christmas Eve, but talks have continued through the night on the details of an agreement. (Photo by Victoria Jones/PA Images via Getty Images)
An anti-Brexit protester shouts through an over-sized loud hailer at the gates of Downing Street, London. The UK and European Union are on the threshold of striking a post-Brexit trade deal. An announcement is expected on Christmas Eve, but talks have continued through the night on the details of an agreement. (Photo by Victoria Jones/PA Images via Getty Images)
Screen grab taken from PA Video of Larry the Cat stalking a pigeon in Downing Street, London. (Photo by Luke Powell/PA Images via Getty Images)
24 December 2020, Berlin: A flag hangs at the British Embassy. The European Union and Britain have moved towards a deal in the dispute over a Brexit trade pact. Photo: Christophe Gateau/dpa (Photo by Christophe Gateau/picture alliance via Getty Images)
A man cleans the street in front of 10 Downing Street, London. The UK and European Union are on the threshold of striking a post-Brexit trade deal. An announcement is expected on Christmas Eve, but talks have continued through the night on the details of an agreement. (Photo by Victoria Jones/PA Images via Getty Images)
Drivers mingle out of their cabs as their freight lorries line up in queues contained in Operation Stack on the M20 motorway at Ashford, Kent, United Kingdom on the 23rd of December 2020. Truck drivers have been waiting in operation stack on the M20 motorway for over 48 hours now, France closed its boarders with the UK after a new faster spreading strain of the COVID-19 virus broke out in Kent. (photo by Andrew Aitchison / In pictures via Getty Images)
The Police line as tensions are high between police and drivers who have been waiting over 48 hours for the Port of Dover to re-open, on the 23rd of December 2020, Dover, Kent, United Kingdom. The French border was closed due to a new strain of COVID-19 all travellers are now waiting to receive a COVID-19 test before they can board a ferry to Calais, France. Dover is the nearest port to France with just 34 kilometres (21 miles) between them. It is one of the busiest ports in the world. As well as freight container ships it is also the main port for P&O and DFDS Seaways ferries. (photo by Andrew Aitchison / In pictures via Getty Images)
An aerial view shows lines of freight lorries and heavy goods vehicles parked on the tarmac at Manston Airport near Ramsgate, south east England on December 22, 2020, as the Brexit contingency plan "Operation Fennel" was activated early to cope with lorries waiting to depart the UK, after France closed its borders to accompanied freight arriving from the UK due to the rapid spread of a new coronavirus strain. - The British government said Tuesday it was considering tests for truckers as part of talks with French authorities to allow the resumption of freight traffic suspended due to a new more infectious coronavirus strain. Britain was plunged into fresh crisis last week with the emergence of a fresh strain of the virus, which is believed to be up to 70 percent more transmissible than other forms. (Photo by William EDWARDS / AFP) (Photo by WILLIAM EDWARDS/AFP via Getty Images)
NEWLYN, ENGLAND - DECEMBER 22: Fishing trawler Emma-Louise leaves port after the last fish market of the year on December 22, 2020 in Newlyn, England. The post-Brexit EU/UK trade deal is still being negotiated with only ten days to go until the deadline passes and the UK officially leaves the European Union. Fishers at Newlyn harbour, one of the UK's largest fishing ports, are preparing for new rules on the export of their fish to the EU from January 1st and their return to work on January 4th. (Photo by Hugh Hastings/Getty Images)
NEWLYN, ENGLAND - DECEMBER 22: Staff of W Stevenson & Sons Ltd sort purchased fish into boxes at the last early morning Fish Market of the year at Newlyn Harbour on December 22, 2020 in Newlyn, England. The post-Brexit EU/UK trade deal is still being negotiated with only ten days to go until the deadline passes and the UK officially leaves the European Union. Fishers at Newlyn harbour, one of the UK's largest fishing ports, are preparing for new rules on the export of their fish to the EU from January 1st and their return to work on January 4th. (Photo by Hugh Hastings/Getty Images)
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Mr Blackford continued: "Industries and communities across Scotland will face higher costs and reduced access to EU markets.
"Benefits of EU membership, including our right to live, work and study across Europe will be stripped away. Justice and security cooperation will be diminished. Even the broken promises made to our fishing communities have turned out to be another Tory pack of lies.
"With the Labour Party lining up behind Boris Johnson, it is clear Westminster will impose this hard Tory Brexit regardless of how Scotland votes but it is not being done in our name. It is a disaster for Scotland."
But Mr Jack insisted Scots would expect their MPs to "do the right thing" and back the agreement in Wednesday's Commons vote.
The UK Government minister said: "We have secured a historic Free Trade deal with the EU that delivers for Scotland and the whole of the UK.
"This is a deep and wide-ranging deal, covering trade, security, travel, transport, energy, health and social security.
"As Parliament prepares to vote on the deal this week, I urge all Scottish MPs to give it their wholehearted support."
Mr Jack continued: "Outside the EU, the UK can sign our own trade deals around the world, bringing new opportunities for exporters and some of Scotland' most iconic products.
"For our farmers, the deal avoids tariffs on their world-beating Scotch lamb and beef.
"For our fishermen and coastal communities, the deal delivers what we promised. We are regaining control of our waters, we are restoring our status as an independent coastal state and, even during the five-year adjustment period, there will be a big overall increase in our share of the catch in our waters.
"As we leave the Common Fisheries Policy, our fishermen will also enjoy near-exclusive access to inshore waters up to the historic 12-mile limit."
The Scottish Secretary insisted: "The deal is good news for Scotland and I believe it is now time to move on from the Brexit debate and join forces in embracing our exciting future.
"Whether Leaver or Remainer in 2016 we need to come to together to make the most of our new opportunities. The people of Scotland will expect their MPs to do the right thing on Wednesday and vote for the deal.
"They will not easily forgive those who reject this Free Trade Agreement or throw their weight behind a no-deal Brexit."