Jacob Rees-Mogg has warned Brexiteers the Government will have to make compromises to get a deal but insists they can trust Boris Johnson not to concede too much to Brussels.

The Leader of the Commons, who was a thorn in the side of Theresa May over Brexit before joining Mr Johnson’s administration, said the Prime Minister had dedicated his political career to the cause of EU withdrawal.

His comments will be seen as a sign of nervousness that hardline Tory Brexiteers could scupper any agreement Mr Johnson is able to reach, just as they thwarted his predecessor.

They come as UK and EU officials were continuing to negotiate through the weekend in an attempt to agree the basis of a deal which could be put to EU leaders at this week’s crucial Brussels summit starting on Thursday.

Writing in The Sunday Telegraph, Mr Rees-Mogg said: “In the final stages of the Brexit negotiation, compromise will inevitably be needed, something even the staunchest Leavers recognise albeit unwillingly – but as a Leaver Boris can be trusted.

“He wants to take back control and has dedicated his political career to this noble cause. If he thinks the ship of state is worth an extra ha’porth of tar he deserves support.”

His comments came as the DUP, whose votes are likely to be crucial to getting a deal through Parliament, fired a warning shot to the Prime Minister over a reported compromise to end the deadlock over the Northern Ireland backstop.

Deputy leader Nigel Dodds warned the mooted plan – reportedly being discussed by EU and UK officials in Brussels in the wake of Mr Johnson’s meeting last week with Irish premier Leo Varadkar – “cannot work”.

Reports from the Belgian capital claimed the Prime Minister had sought to revive a proposal first put forward by Mrs May for a customs partnership between the UK and the EU.

The scheme, intended to avoid the need for customs controls on the island of Ireland, would see Northern Ireland remain politically in a customs union with the EU but it would be administered by the UK.

Brexit
DUP deputy leader Nigel Dodds has warned that a reported Brexit compromise ‘cannot work’ (Aaron Chown/PA)

However Mr Dodds told the Italian La Repubblica newspaper that Northern Ireland “must stay in a full UK customs union, full stop”.

“It cannot work because Northern Ireland has to remain fully part of the UK customs union,” he said.

He added: “There is a lot of stuff coming from Brussels, pushed by the Europeans in the last hours, but one thing is sure: Northern Ireland must remain fully part of the UK customs union. And Boris Johnson knows it very well.”

British officials have so far remained tight-lipped in the face of the reports.

The reported plan would create a customs border in the Irish Sea with goods travelling from the rest of the UK to Northern Ireland being subject to tariffs which Britain would collect on behalf of the EU.

Businesses would then be able to claim a rebate once they had shown the goods were for consumption in the UK market.

However it would mean that Northern Ireland would be able to benefit from any post-Brexit trade deals the UK struck with other countries around the world.

The EU’s chief negotiator Michel Barnier is due to brief EU ambassadors and MEPs on Monday on progress in the talks.