British MPs on Monday voted narrowly in favour of a motion asking the government to publish its impact assessments for a no-deal Brexit, in a new blow for Prime Minister Boris Johnson.
The motion, which passed by 311 votes to 302, also asks the government to publish communications between government officials over their plans for the suspension of parliament.
It is the fourth defeat the British prime minister has endured since he became leader.
The vote came ahead of a second attempt by the British prime minister to force an October general election, which is widely expected to be rejected by MPs.
Meanwhile, the Speaker of the House of Commons, John Bercow, announced he is standing down from the role on 31 October after ten years.
Many MPs are deeply opposed to Johnson's threat to end Britain's 46-year-old membership of the EU at the end of next month without agreeing any new arrangements.
In Monday's vote, MPs also asked the government to publish communications, including WhatsApp messages and private emails, from certain advisers relating to Johnson's decision to suspend parliament for five weeks.
The motion is not legally binding but is politically difficult to ignore.
The premier says the so-called prorogation is a routine move to allow his premiership, which only began in July, to start afresh with a new legislative programme.
But MPs see it as an attempt to silence them in the run-up to Brexit and believe documents will prove it.
Government minister Michael Gove warned their "desire to rifle through private correspondences of advisers is to set aside legal precedent and the rights of citizens".
Britons voted in June 2016 to leave the EU but after three years of political wrangling, parliament still cannot decide how to implement the decision.
Johnson says he is working to revise the deal agreed by his predecessor, Theresa May, which MPs rejected -- but insists Brexit must happen next month no matter what.
However, he has no majority in the House of Commons, having expelled 21 MPs from his own Conservative party last week for voting for the rebel legislation.
The bill, which became law Monday, would force Johnson to delay Brexit to January or even later if he cannot get a deal with Brussels at a crucial EU summit on October 17-18 -- or persuade MPs to back no deal.
In response, the premier called a snap election for early next month, but MPs refused to support him -- and a second attempt later on Monday also looks doomed as it is opposed by opposition leaders.