May's senior ministers, summoned to her country retreat at Chequers, all backed the soft-Brexit plan she aims to send to Brussels for EU approval. Brexit-supporting Conservative MPs were quick to voice their concerns on Saturday, Xinhua news agency reported.

Jacob Rees-Mogg, who is leader of the influential European Research Group of pro-Brexit Conservatives, told the BBC early morning Today programme: "It is possible that this deal is worse than a no deal Brexit."

Rees-Mogg, once spoken of as a successor to May as Prime Minister, said he was waiting to see the full details of the proposals, adding: "If it turns out that it is a punishment Brexit, that it is keeping us in the European Union in all but name, I will stick to the Conservative party's manifesto commitments and will not vote for it."

Media reports on Saturday said May had told her cabinet ministers they were now have to adhere to the convention of cabinet responsibility. This would prevent any of them from speaking against the proposals agreed at her Chequers meeting.

It was also seen, according to the media, as a stark warning to Foreign Secretary Boris Johnson that he would lose his job is he makes any outspoken comments.

John Longworth, one-time director general of the British Chambers of Commerce and co-chairman of the pro-Brexit group Leave Means Leave, pulled no punches with his message, saying: "Those who campaigned for Leave but have not resigned will see their reputations in tatters."

Writing in the Daily Telegraph, Longworth accused May of totally misleading the 17.4 million British people who voted leave, "and left it as late as possible to reveal that she remains a stubborn Remainer".

"We are faced with becoming a vassal state of the EU, they have us exactly where they want us - unable to compete, taking enormous quantities of their products at inflated prices, protected from global competition by the fortress Europe tariff and regulatory wall and impeded from doing trade deals around the globe," added Longworth.

Elsewhere there was a sigh of relief that the government finally had a proposed deal to present to Brussels.

Conservative MP Andrea Leadsom, who is Leader of the House of Commons, said on her social media site: "As a passionate Brexiteer with huge optimism about future as a free trading nation, I agree with the PM (May) that keeping the UK together is vital. Alignment on goods, with Parliament sovereign on each decision, free to trade, no more vast payments, ending free movement - good for UK."