Theresa May is potentially facing a fresh Tory cabinet rebellion as concern grows that she is planning to lock the UK in a customs union with the European Union (EU) for an unlimited period.

Some pro-Brexit cabinet ministers reluctantly signed up to the Prime Minister’s Chequers Brexit plan and did not expect her to make so many further concessions to the bloc.

Sources have also claimed this week that Mrs May could keep the UK tied to the bloc’s restrictive laws and regulations of the environment and labour.

The EU has consistently blocked British attempts to agree on a finish date for the “backstop” that will keep the whole UK in a customs union, and now many Conservative Brexiteers are arguing a potentially unlimited time frame is unacceptable, the BBC reports.

Cabinet ministers including trade secretary Liam Fox, environment secretary Michael Gove, Brexit secretary Dominic Raab, and foreign secretary Jeremy Hunt have reportedly expressed concerns.

And Commons leader Andrea Leadsom is reportedly “thinking carefully about whether she could put up with such a compromise” amid speculation she could resign, the BBC claims.

Sources say the EU is now ready to accept Mrs May’s proposal of keeping the entire UK in the customs union after Brexit and the transition period.

Fresh Concessions: Appeaser Theresa to Lock UK in Customs Union, Follow EU Environment and Labour Laws https://t.co/PBH7PHmD6j — Breitbart London (@BreitbartLondon) October 10, 2018

The only other option they have offered the UK is to keep Northern Ireland in the customs union and divide the UK with checks in the Irish Sea – something the Democratic Unionist Party (DUP) has roundly rejected.

The DUP is propping up Mrs May’s minority government and on Wednesday they threatened to vote down the budget and move to topple the government if the Prime Minister breaches their Brexit “red lines”.

On Tuesday, former Brexit minister Steve Baker said up to 80 Tory MPs are considering voting against the Prime Minister’s “half-in-half-out Chequers [Brexit] deal”.

The prominent Brexiteer said that at least 40 MPs would vote down Theresa May’s deal, even after “every possible technique” is used by the Government to persuade or force MPs to toe the party line.

His former boss David Davis, who resigned at the same time, also wrote to Tory MPs warning of “dire” electoral consequences if May continues to pursue a Chequers plan.