UK Prime Minister Theresa May was accused of "misleading Parliament" as the full legal advice on her Brexit deal was published on Wednesday, a day after her ministers were found in contempt of Parliament for providing only a legal overview of the deal.
A crunch vote on May's Brexit deal is scheduled to take place next week while her ministers continued with attempts to win over rebel MPs on the Prime Minister's agreement, with eight hours of debate on the security and immigration aspects of the pact.
In the documents, the Attorney General Geoffrey Cox said the proposed backstop arrangement with the EU to prevent a hard Irish border could "endure indefinitely".
He said the UK would not be able to "lawfully exit" the arrangement without a subsequent political agreement and this could lead to stalemate.
The Scottish National Party said May had "concealed the facts" after the advice came out.
However, the Prime Minister rejected the accusation, saying the legal position had been set out clearly.
The British government agreed to publish the full advice after being found in contempt of the Parliament by an MP vote on Tuesday.
The Irish backstop, a key feature of the EU withdrawal agreement, would see the whole of the UK remain in a single customs territory with the EU until their future relationship was sorted out, the BBC reported.
The Democratic Unionists said the legal viewpoint was "devastating" for May's prospects of getting the backing of MPs for her deal in the vote on December 11.
The government said that the Attorney General's analysis of the Brexit deal, that was published on Monday, was adequate and disclosing the full advice would be against the national interest.
While the UK would have no unilateral right to withdraw from the backstop - - a measure designed to prevent the return of physical checks on the Irish border - - May insisted neither the UK nor the EU wanted the backstop to come into force in the first place, according to the BBC.
Labour said the advice showed the "central weakness" of the Prime Minister's Brexit deal while the Liberal Democrats said it would leave the UK trapped in a "Brexit hamster wheel".
The government suffered three embarrassing defeats on Tuesday on the role that MPs will play if May's deal is rejected as well as the disclosure of the legal advice.
International Trade Secretary Liam Fox warned there was a risk of Parliament trying to "steal Brexit from the British people" if May's agreement was rejected.