On the eve of a summit of EU leaders in Brussels, Theresa May has come under continuing pressure over increasingly open Government divisions on Brexit.
Labour leader Jeremy Corbyn told the House of Commons that the Prime Minister was having to "negotiate round the clock" with her own Cabinet to prevent it from collapsing.
But Mrs May insisted that the Government was working to ensure that Britain was "fit for the future" and ready to leave the EU on Brexit Day on March 29 2019.
Meanwhile, the Chief Constable of Northern Ireland warned that Brexit has the potential to spark civil disorder in the six counties, if it results in certain communities feeling "less secure and more vulnerable about their own identity".
And former PM Tony Blair called on Mrs May to make preparations to delay the date of Brexit unless she and her Cabinet were able to decide swiftly on a course of action.
Thursday's European Council summit in Brussels is expected to give little time to Brexit, with EU states focusing on migration and Russia, though leaders of the remaining 27 members will receive an update on negotiations in Mrs May's absence on Friday.
All eyes are now on a Cabinet awayday at Chequers at the end of next week, at which the Prime Minister aims to secure Cabinet backing for her vision of Britain's future relations with the EU.
The plans, covering issues such as trade and security, are due to be set out in a long-awaited white paper next month which is expected to outline in detail how the PM envisages Britain engaging in future with the EU's single market and customs union.
Ministers have been openly jockeying for position ahead of the get-together, with Jeremy Hunt dismissing Airbus concerns about the impact of a no-deal withdrawal from the EU, while Greg Clark insisted businesses should be "listened to with respect".
In response to speculation that Mrs May could seek continued membership of the single market for goods, Brexit minister Steve Baker tweeted: "Government policy is, and must remain, to leave the EU's internal market as we leave the EU."
And Jacob Rees-Mogg, chairman of the influential European Research Group of pro-Brexit Tories, accused Chancellor Philip Hammond of working with business leaders to raise concerns about leaving the EU.
"I think there is co-operation between the Remainers in the Cabinet and some businesses, some of the more politicised businesses," Mr Rees-Mogg told Sky News.
Asked who in the Cabinet he meant, Mr Rees-Mogg replied: "Oh, the Chancellor. Boris Johnson was quite right when he said the Treasury is the beating heart of Remain, that's obvious."
Going on the attack at Prime Minister's Questions in the Commons, Mr Corbyn urged Mrs May to take the "phoney threat" of a no-deal Brexit off the negotiating table.
"No deal is a bad deal, but isn't the truth that the real risk to jobs in our country is a Prime Minister who is having to negotiate round the clock with her own Cabinet to stop it falling apart, rather than negotiating to defend jobs of workers in this country?" asked the Labour leader.
The Prime Minister defended her Government's record, insisting that Britain is a country "fit for the future and leaving the European Union on the 29th of March 2019".
In a speech in London, Mr Blair said he still believed that Brexit "can and should be stopped" as he hit out at Mrs May's handling of the negotiations.
"Up to now, the negotiation with Europe has been conducted by civil servants in a state of despair overseen by politicians in a state of denial," he said.