Raab said he could not "reconcile the terms of the proposed deal." Photo: Reuters

The move comes as a huge blow to British Prime Minister Theresa May. Raab was appointed the Brexit secretary only in July after David Davis resigned in protest against "a business-friendly" deal to leave the EU.

The two junior ministers who also resigned on Thursday are Suella Braverman and Shailesh Vara.

"I regret to say that, following the Cabinet meeting yesterday on the Brexit deal, I must resign," Raab said. May's plan threatened the integrity of the UK, he said.

"I cannot reconcile the terms of the proposed deal with the promises we made to the country in our manifesto at the last election. This is, at its heart, a matter of public trust," he said in his resignation letter, published on his Twitter account.

Draft Agreement

McVey, a Brexit hardliner, was the second senior minister to quit over May's draft agreement.

"The deal you put before the cabinet yesterday does not honour the result of the referendum," she told the prime minister in her resignation.

EU leaders will meet on November 25 to endorse the divorce deal that has been stalled over lack of consensus.

May will set out the terms of the draft withdrawal agreement on Thursday to the House of Commons, which must approve the deal before the UK leaves the EU on March 29.

The prime minister secured the backing of her cabinet for the draft agreement on Wednesday, after a five-hour meeting.

"The collective decision of the government was that the cabinet should agree to the draft agreement and the outlying political declaration," May said on Wednesday.

"This is a decisive step, which allows us to move on and finalise the deal in the days ahead," she added. "These decisions were not taken lightly, but I firmly believe they were in the national interest."

The main opposition Labour Party has also criticised the draft deal, saying it "breaches the prime minister's own red lines".

"This government spent two years negotiating a bad deal that will leave the country in an indefinite halfway house," Jeremy Corbyn, the Labour Party leader, said.