Three pro-EU cabinet ministers have issued a blunt warning to Tory Brexiteers that Parliament will prevent them forcing a "disastrous" no-deal break with the EU.
Amber Rudd, Greg Clark and David Gauke said Brexiteers in the European Research Group (ERG) will only have themselves to blame if Britain's departure from the EU is delayed.
Their comments are likely to be seen as a thinly veiled warning that they could defy Theresa May to back moves by MPs to prevent a no-deal Brexit in next week's crunch Commons vote.
The Prime Minister has repeatedly insisted Britain will leave on March 29 as planned.
But writing in the Daily Mail, the ministers said it was clear a majority of MPs would support an extension to the Article 50 withdrawal process rather than see no-deal.
They said leaving without an agreement in place with Brussels would weaken national security, "severely" damage the economy, and risk the break-up of the United Kingdom.
"If there is no breakthrough in the coming week, the balance of opinion in Parliament is clear - that it would be better to seek to extend Article 50 and delay our date of departure rather than crash out of the European Union on March 29," they said.
"It is time that many of our Conservative party colleagues in the ERG recognise that Parliament will stop a disastrous no-deal Brexit on March 29.
"If that happens, they will have no-one to blame but themselves for delaying Brexit."
They also praised the Prime Minister's "resiliance" and accused Boris Johnson and Jacob Rees-Mogg of brushing aside the consequences of Brexit.
The letter added: "A No Deal Brexit will mean that those whose lives straddle the Northern Ireland/Republic of Ireland border will become much more complicated."
Moderate Conservative MPs are among a group of 100 Leavers and Remainers who have already written to Chief Whip Julian Smith to warn they are ready to vote for a delay Brexit if the "intransigence" of hard-line Brexiteers means Mrs May's deal is again rejected by the House.
Andrew Percy, one of the leaders of the Brexit Delivery Group, said "dozens" of his colleagues would be prepared to rebel in order to block the UK leaving the European Union without a deal.
In comments apparently aimed at the European Research Group (ERG) of Brexiteers, Mr Percy warned they risked the prospect of Brexit not happening at all unless they compromised and backed a deal.
"Some of my colleagues have got to recognise that the game they have thus far been playing with regards to this whole process is not going to end well for them and could potentially end with the delaying of, perhaps even no Brexit - which some of us have spent a lot of our parliamentary and political careers campaigning for," he told BBC Radio 4's Today programme.
On Wednesday, the Commons is expected to consider an amendment tabled by Labour MP Yvette Cooper and Conservative former minister Sir Oliver Letwin enabling the House to extend the Article 50 withdrawal process if there is no deal by mid-March.
A similar amendment was defeated by MPs last month, but there is speculation that enough Tory rebels, alarmed that there is still no-deal in place, could be prepared to back it this time round for it to pass.
Talks with Brussels are due to resume next week as ministers continue to seek legally binding changes to the Northern Ireland backstop that will enable Mrs May to finally get the withdrawal agreement through the Commons.
MPs in the ERG have warned they will again vote against the deal if they are not satisfied with the changes.
Downing Street has said if there is no deal by Tuesday, the PM will make another statement to the House and table an amendable motion to be debated and voted on the following day.
Before that Mrs May will attend the two-day EU-League of Arab States summit in the Egyptian Red Sea resort of Sharm el Sheikh starting on Sunday.
She is expected to hold one-to-one meetings in the margins of the main conference with key EU figures including European Council president Donald Tusk, German Chancellor Angela Merkel and Irish premier Leo Varadkar.
No 10 has played down the prospect of a breakthrough, and there is speculation that Mrs May will say she intends to come back to the House again in two weeks time when she addresses MPs on Tuesday.
However it is unclear whether that will be enough to stave off a revolt by MPs alarmed at the prospect of no-deal - including potential ministerial resignations.
The latest development came at the end of an extraordinary week which saw eight Labour MPs and three Tories quit their parties to form a new Independent Group in the Commons supporting a second referendum.
Additional reporting by Press Association