Britain is heading full throttle for a total write-off of Brexit if it continues with Theresa May’s disastrous plans for the Irish border, Boris Johnson has claimed.

The backstop deadlock is being used to force the UK into becoming a vassal state and the talks are on course to end in a “spectacular political car crash”,  according to the former foreign secretary.

Mr Johnson said the European Union’s fallback position for the Irish border would  mean Northern Ireland was “annexed” by Brussels.

Alternative plans set out by Mrs May would “effectively” keep Britain in the bloc, he added.

It comes amid reports the EU is preparing to accept use of technology to avoid the need for new border infrastructure.

Environment Secretary Michael Gove described the PM’s divisive Chequers plan as the “right one for now” and suggested it could be altered by a future leader.

But Mr Johnson said the exit proposals were taking the country in the wrong direction.

Writing in The Daily Telegraph, he said: “If the Brexit negotiations continue on this path they will end, I am afraid, in a spectacular political car crash.”

“If we are to get out of this mess, and get the great British motor back on track, then we need to understand the Irish backstop, and how it is being used to coerce the UK into becoming a vassal state of Brussels,” he added.

The EU’s backstop would leave a border down the Irish sea while the UK’s proposal left it “volunteering” to “remain effectively in the customs union and large parts of the single market until Brussels says otherwise”, Mr Johnson said.

“Both versions of the backstop are disastrous,” he wrote. “One threatens the union; the other version – and its close cousin, Chequers – keep us effectively in the EU, as humiliated rules takers.

“We need to challenge the assumptions of both these Irish backstops, or we are heading full throttle for the ditch with a total write-off of Brexit.

“We are straining at the gnat of the Irish border problem – in fact we haven’t even tried to chew the gnat – and we are swallowing the camel of EU membership in all but name.”

Mr Johnson said that if Chequers was adopted “it would mean that for the first time since 1066 our leaders were deliberately acquiescing in foreign rule”.

Mrs May said there needs to be “friction-free” movement of goods across the Irish border, without customs or regulatory checks between the UK and EU, after Brexit.

Northern Ireland after Brexit: the options
(PA Graphics)

She said that the counter-proposal will not “solve the issue of no hard border by having a hard border 20km inside Ireland”.

“The people of Northern Ireland deserve to be listened to in these negotiations by the UK Government as do people elsewhere in this country,” she told the BBC.

“I want to ensure that as we go forward we have that strong union… Northern Ireland is part of the United Kingdom. They don’t want a hard border between Northern Ireland and Ireland.

“The only proposal that’s been put forward that delivers on them not having a hard border and ensures that we don’t carve up the United Kingdom, is the Chequers plan.”

EU chief negotiator Michel Barnier is drafting a new “protocol” text that includes the use of technology to minimise checks at the Irish border, according to The Times.

Diplomatic notes seen by the paper state: “The biggest unsolved problem is Northern Ireland.

“There is a political mobilisation in the UK in this regard. Therefore, we are trying to clarify the EU position.”