Boris Johnson has condemned one of the UK's biggest business groups after it suspended its director general for suggesting the UK could have a brighter future outside the European Union.
The London mayor claimed that British Chambers of Commerce leader John Longworth had become a victim of "Project Fear" - the label used by Brexit campaigners to criticise the tactics used by David Cameron and his allies backing a Remain vote.
His comments came as Justice Secretary Michael Gove warned that the UK's membership of the EU could make the country less safe.
Mr Johnson, who is a prominent Brexit backer, said the BCC's decision was "scandalous" and claimed Mr Longworth had been "crushed" by the "agents" of Project Fear.
Number 10 strenuously denied involvement in Mr Longworth's suspension.
The BCC is remaining neutral in the referendum campaign and Mr Longworth stressed he was giving his personal opinion as he used his keynote speech at the organisation's conference on Thursday to say the UK might be better off outside the EU.
Mr Johnson said: "It is absolutely scandalous that John Longworth has been forced to step aside.
"This is a man who reached the conclusion - after long reflection and a lifetime's experience of business - that it would be better to vote Leave.
"His verdict reflects the reality - that the EU has changed out of all recognition from the Common Market that this country joined.
"He speaks for the many small and medium sized businesses - the lifeblood of the economy - who cannot understand why they should comply with more and more regulation, over which this country has no democratic control.
"Only 5% cent of UK firms do business with the rest of Europe, and yet they must obey 100% of EU legislation.
"The British public deserve to have the facts put before them. They deserve a proper debate.
"It cannot be right that when someone has the guts to dissent from the establishment line, he or she is immediately crushed by the agents of Project Fear."
The Sunday Telegraph said a friend of Mr Longworth claimed Downing Street had "bullied" and been "putting pressure" on BCC board members to suspend their director-general.
But a No 10 source said: "This is simply not true. This is a matter for the BCC. No pressure was put on the BCC to suspend John Longworth."
Meanwhile Mr Gove joined forces with Mr Johnson in an attempt to undermine the Prime Minister's repeated claims that EU membership made the UK "stronger" and "safer".
The Justice Secretary told the Sunday Times: "I think overall our national security is strengthened if we are able to make the decisions that we need and the alliances that we believe in outside the current structures of the of the European Union."
He claimed EU judges had taken decisions against the UK's national interests by dictating "what our spies can do and whether we can be kept safe".
Mr Gove added: "Our security and sovereignty stand together. I believe that there are better opportunities to keep people safe if we are outside the European Union."
Mr Johnson said the EU had taken "decisions that are inimical to our ability to mount serious surveillance operations against terrorists".
He added: "The power to take decisions about deporting people or about counter-terrorist surveillance is being taken away from the UK."