The British government is to hand over analysis to the UK parliament which warns of the negative impact of Brexit in a bid to deflect accusations that ministers are badly prepared for leaving the EU.
The report piled more pressure on Prime Minister Theresa May, who is under fire from some in her own Conservative Party for lacking leadership and a clear Brexit exiting plan.
The opposition Labour Party is trying to force the government into handing over the report, entitled "EU Exit Analysis - Cross Whitehall Briefing" by using an ancient parliamentary procedure.
One government junior Brexit minister, Robin Walker, told parliament that if lawmakers voted in favour of publishing the report, it could be seen "on a strictly confidential basis".
"Let me start by saying that the government will not be opposing this motion today," he said.
The report, which the government has called a partial piece of work that had yet to be signed off by ministers, said the economy would be worse off after Brexit whether Britain left the EU with a free trade deal, single market access, or with no deal at all.
On Tuesday, another junior Brexit minister, Steve Baker, rebuffed calls for the government to release the full report by saying it was not ready and that lawmakers should be cautious because analysis by officials was often wrong.
Phillip Lee, a minister at the justice department, was rebuked on Wednesday for expressing on Twitter his suggestion that if the report were true "there would be a serious question over whether a government could legitimately lead a country along a path that the evidence and rational consideration indicate would be damaging".
Government aides have said the paper leaked to BuzzFeed News had not been signed off by ministers nor had considered the government's preferred goal of a bespoke future relationship with the EU after leaving.
But it has raised further questions over how prepared the government is for the complicated negotiations to end Britain's membership of the EU.
"There is a serious point here," said Labour's Brexit policy chief Keir Starmer.
"Is it seriously government policy that impact assessments are so unreliable that it is better to proceed without them?
"We need an informed debate including the likely economic impact of different approaches - publication is needed in the name of transparency," he told parliament.
