Documents apparently setting out how the Prime Minister would sell an exit package to the public were published on Tuesday by the BBC.

Downing Street distanced itself from the blueprint but the document fuelled claims among Tory Brexiteers that a deal has secretly been secured.

Labour’s Sir Keir Starmer, meanwhile, is heading to Brussels to warn of the dangers of Britain and the European Union striking a loose agreement on future relations.

Theresa Mays Cabinet is on standby for fresh talks to agree a Brexit deal amid claims by Tory Leavers she has already reached an agreement.

The shadow Brexit secretary claims Tory divisions have stalled progress on trade links and will mean years of further negotiations.

Mrs May told senior ministers on Tuesday that she would not agree a withdrawal deal with the EU “at any cost”.

The PM assured her top team that there would be another Cabinet before any agreement is settled.

No extra meeting has yet been scheduled ahead of the regular weekly gathering next Tuesday but ministers could gather as soon as Thursday.

Mrs May will give a “we have delivered on the referendum” speech to the CBI conference on November 19, according to documents supposedly setting out plans to win over support for a Brexit deal.

The “grid” document said MPs would be told to put personal interests aside to back an agreement on November 27.

Former Brexit minister Steve Baker told The Daily Telegraph: “It looks like exactly the kind of back-of-the-envelope post-exit plan to sell a rubbish deal I would have expected.

“For months we have expected an orchestrated campaign following a fabricated row over the backstop.”

Jacob Rees-Mogg, chairman of the European Research Group of Tory Eurosceptics, told the newspaper: “There are rumours a deal has been done without keeping the Cabinet properly informed ... the Chequers proposals undermined trust.

“If there is an attempt to soften up and hoodwink people there will be no trust left.”

But No 10 said the “childish language” and misspelling in the notes, which includes the incorrect spelling of the Irish prime minister’s name, should make it clear it “doesn’t represent the Government’s thinking”.

Sir Keir said any Brexit package the Government secures must provide detailed answers on future trade, customs, immigration, security, research and collaboration and repeated warnings that Labour would vote against “anything less”.

He is meeting European Commission vice-president Frans Timmermans, Markus Winkler, deputy secretary general of the EU Parliament, and Roberto Gualtieri, who sits on the parliament’s Brexit Steering Group.

Sir Keir said: “This is crunch time in the Brexit negotiations. Yet Government divisions and delays mean that little time has been spent debating what our future trading and security relationship will be after Brexit.

“Months of deadlock in Theresa May’s Government mean we’re facing continued uncertainty and the prospect of years of further negotiations over our future relationship with the EU.

“A blind Brexit could prolong business uncertainty and provide insufficient guarantees to protect jobs, the economy and rights. Whether you voted leave or remain, nobody voted for the purgatory of permanent negotiations.

“Theresa May and Dominic Raab promised that the Brexit deal put before Parliament will be ‘detailed, precise and substantive’.

“That is exactly what Labour expects and what I will be discussing in Brussels. If the final deal is anything less than the Government has promised, Labour will not support it.”

Cabinet on standby for talks amid hopes of Brexit deal