Mr Brexit leads mini anti-May rebellion

It would make British parliamentary rule "illusory", handed "control of large swathes of our economy to the EU", and was "certainly not returning control of our laws in any real sense," he added.

May had put Britain in a "weak negotiating position", he also said, calling himself a "reluctant conscript" to her leadership.

His rebellion was joined by two junior ministers, Steve Baker and Suella Braverman.

It was also egged on by a handful of hard-Brexit MPs, led by Jacob Rees-Mogg, who said in a letter to May that her plan was the "worst of all worlds" and would leave the UK stuck "as a vassal state in the EU's legal and regulatory tarpit."

"That is not something that this country voted for, it is not what the prime minister promised," Rees-Mogg said.

The anti-May rebellion has yet to gather traction, as two other hard-Brexit ministers took different positions.

Environment secretary Michael Gove backed May's plan in a BBC interview on Sunday.

"I'm a realist," he said.

"One of the things about politics is that you mustn't, you shouldn't, make 'the perfect' the enemy of 'the good', and one of the things about this compromise is that it unites the cabinet," he said.

Boris Johnson, Britain's foreign minister, gave silent assent to May's EU blueprint, but he was also quoted by the BBC as having called her plan "a big turd" in private remarks.

If May has to fight a leadership challenge that would cost time and energy just eight months before the UK leaves the EU in March 2019.

Davis' departure also poses the question of who she can appoint to take his place that is both versed in the detail of the negotiations and acceptable to her warring cabinet.

'Lazy' Davis

His resignation might make little difference to day-to-day talks between British and EU officials in the short term, however.

Davis met his EU counterpart Michel Barnier just twice in Brussels and once in London this year.

The 69-year old, who had not held a government post for almost 20 years before this one, often skipped or cut short EU meetings and was photographed without briefing notes.

He was as "thick as mince, lazy as a toad, and vain as Narcissus," according to remarks last year by Dominic Cummings, the former chief of Leave.EU, a pro-Brexit campaign group.

Davis also lacked "stability and accountability" and showed an "lack of involvement", according to European Commission president Jean-Claude Juncker's past assessment.

But if anyone wanted to question his professionalism, they should "check my travel schedule - it starts early in the morning and ends after most people have gone to bed," Davis said in his own defence against Cummings.

The new British blueprint, adopted at a government meeting on Friday, proposed a "facilitated customs arrangement" with the EU.

It would adopt the EU's "common rule book" on goods, but not services, and would use high technology to impose EU tariffs on overseas products entering Europe via the UK.

"I am sorry that you have chosen to leave the government … when we are only eight months from the date set in law when the United Kingdom will leave the European Union," May said in her reply to Davis.

'Special partnership'

Her EU plan amounted to "a deep and special partnership including a comprehensive free-trade and customs agreement", she said.

But it would also leave the UK "as an independent, self-governing nation" on the world stage once again, she added.

It meant "ending free movement and taking back control of our borders," she said, echoing the hard-Brexit camp's rhetoric.

It also meant "no more sending vast sums of money each year to the EU" and "restoring the supremacy of British courts by ending the jurisdiction of the European Court of justice in the UK," she said.

The prime minister will, on Monday, defend her plan in parliament, while looking for Davis' replacement.

She must also prepare to host Donald Trump, the window-breaking US president, who is due in London for the first time this week amid expected street protests.