A cross-party group of politicians including Liberal Democrats leader Jo Swinson have launched legal action to prevent Boris Johnson suspending Parliament to force through a no-deal Brexit.
The challenge has come amid reports European Union officials believe Mr Johnson has no intention to negotiate a new deal.
The Prime Minister told talkRADIO he plans to leave the EU “do or die, come what may” and talks between his administration and the EU have stalled.
A group of more than 70 MPs and peers, including Labour MP Jess Phillips and SNP MP Joanna Cherry, have joined anti-Brexit group the Good Law Project to launch the legal action.
They have asked the Court of Session in Scotland to declare the Prime Minister cannot lawfully advise the Queen to close down Parliament, calling it “the act of a dictator”.
The legal papers state that seeking to suspend, or prorogue, Parliament to prevent members from voting “is both unlawful and unconstitutional”.
“The exercise of the power of prorogation would have irreversible legal, constitutional and practical implications for the United Kingdom,” it said.
No date has been set to hear the case, with fewer than 90 days until a no-deal Brexit could occur on October 31.
Good Law Project founder Jolyon Maugham QC said the number of politicians getting behind the case shows “how profoundly our politics has declined”.