Senior Tory Eurosceptics have written to Theresa May claiming her accord with the EU to delay Brexit may be illegal.
Sir Bill Cash, Suella Braverman and others tell the prime minister that MPs and lawyers have “serious legal objections” about Brexit being pushed to beyond March 29.
It comes after May struck an agreement with EU leaders at a summit in Brussels last week to extend the UK’s membership until April 12 - or May 22 if she succeeds in passing her withdrawal agreement through parliament.
May’s administration sought the delay after MPs voted for a Commons motion to extend the process.
A statutory instrument (SI), a parliamentary device used to create laws, will be used to officially remove the March 29 date from Brexit legislation and is due to be debated by the House of Commons on Wednesday.
The Tory MPs claim May’s decision to seek parliament’s approval for the SI after the event “called into question the lawfulness of its actions and has (at minimum) created serious legal doubts about the legal situation surrounding the extension”.
The MPs’ letter also makes separate claims about the delay.
It states that May could have made unlawful use of the Royal Prerogative in agreeing to an extension which was “inconsistent with the intention of parliament”.
Legal precedent suggested the PM required an act of parliament to use the prerogative in this way, they said.
They complained the government had presented parliament with a fait accompli instead of “respecting the normal practice” of asking MPs to approve a binding international obligation in advance.
They also said the extension violated the Vienna Convention because it was agreed “in violation of a provision of internal law”.