Boris Johnson's brother resigns and calls for a second Brexit referendum

The resignation is likely to increase pressure on Theresa May More

He said: "Given that the reality of Brexit has turned out to be so far from what was once promised, the democratic thing to do is to give the public the final say".

"We will not under any circumstances have a second referendum", a spokesman said.

Responding to the resignation, shadow Brexit minister Jenny Chapman said: "Jo Johnson is the eighteenth minister to resign from Theresa May's government".

The critique from Johnson underscores the travails that May faces in getting any Brexit divorce deal, which London and Brussels say is 95% done, approved by her own fractious party.

It added: "The prime minister thanks Jo Johnson for his work in government".

He added it would be a "democratic travesty" if Britons were not able to go back to the polls to vote on the terms of the deal that may be struck with Brussels.

The agreement will finalise the country's exit bill of around £39 billion ($50 million), guarantee citizens' rights and see a 21-month transition phase during which London will follow European Union rules.

British and European negotiators will then seek to agree on the long-term future relationship.

European Union envoys were reportedly briefed on Friday that there is a mutual understanding of what the review mechanism should look like, as well as convergence on the Irish backstop plan, which would ensure there's no hard border between Northern Ireland and the Republic of Ireland once Brexit is delivered.

The only alternative on the table, he said, is a no-deal Brexit that would "inflict untold damage" on Britain.

In a blog for Medium, Johnson, brother of arch-Brexiteer and former foreign secretary Boris Johnson, writes: "Although I voted Remain, I have desperately wanted the government, in which I have been proud to serve, to make a success of Brexit: to reunite our country, our party and, yes, my family too". I reject this false choice between the PM's deal and "no deal" chaos.

On Friday the DUP, whose support Theresa May relies on for votes in the Commons, said they could not support any deal which included the possibility that Northern Ireland would be treated differently from the rest of the UK.

Downing Street said last night it would not agree to a second referendum vote under any circumstances and reiterated a promise not to sign the United Kingdom up to any deal which could return a hard border to Northern Ireland.

"My brother Boris, who led the "Leave" campaign, is as unhappy with the government's proposals as I am", Jo Johnson said. "If these negotiations have achieved little else, they have at least united us in fraternal dismay".