Steve Baker of the European Research Group has tabled amendments that could scupper a backstop

Theresa May is facing a rebellion by more than 40 of her MPs if she does not bow to fresh demands from Brexiteers in the next 48 hours.

Downing Street has commissioned urgent legal advice to determine whether the prime minister must face down new demands by the European Research Group that could scupper a key part of the Brexit negotiations.

Steve Baker, a leading officer for the group, has put down amendments to government legislation that would stop Northern Ireland being placed in a different regulatory and customs territory from the rest of Britain without a vote in the Stormont assembly.

The Democratic Unionist Party would be unlikely to vote for this, even if the parliament were not suspended, which it is at present.