Boris Johnson has been heavily criticised for sending an unsigned letter to the EU requesting an extension.
Labour branded the Prime Minister “churlish” and “juvenile” in his attitude as Mr Johnson stressed to Brussels he was only sending the communication at Parliament’s bidding.
After suffering an embarrassing defeat in the Commons over his Brexit plans, the PM got a senior diplomat to send Brussels an unsigned photocopy of the call by MPs to delay withdrawal from the bloc, with a cover note stressing his detachment from the move.
In a second note to European Council president Donald Tusk, the PM said a Brexit extension would be “deeply corrosive”.
The stance is likely to spark a fierce political row, and a possible legal challenge.
Labour’s shadow Chancellor John McDonnell Tweeted: “Johnson is a Prime Minister who is now treating Parliament and the courts with contempt.
“His juvenile refusal to even sign the letter confirms what we always suspected that Johnson with his arrogant sense of entitlement considers he is above the law and above accountability.”
The move came after a defiant Prime Minister told the Commons he will not negotiate a fresh Brexit extension with the EU.
Mr Tusk Tweeted: “The extension request has just arrived. I will now start consulting EU leaders on how to react. #Brexit”
It followed a special Saturday sitting of the Commons where MPs voted by 322 to 306 in favour of an amendment withholding approval of his Brexit deal until legislation to implement it is in place.
The amendment tabled by former Cabinet minister Sir Oliver Letwin was intended to force him to comply with the so-called Benn Act requiring him to seek a Brexit extension.
The PM rang European leaders, including Mr Tusk, declaring that the letter “is Parliament’s letter, not my letter”.
Mr Benn tweeted on Saturday: “After all the bluster, the Prime Minister has tonight sent a letter to the EU asking for an extension.
“A bit churlish not to sign it though.”
Labour leader Jeremy Corbyn tweeted: “Today I told the Prime Minister to obey the law and despite his petulant posturing and bluster he finally has – he’s asked for an extension.”
The development came as the PM wrote to all Tory MPs and peers insisting that he will tell Brussels a further Brexit delay is “not a solution” to the situation.
In a letter to members of the Tory parliamentary party, the PM said: “I will tell the European Union what I have told the British public for my 88 days as Prime Minister: further delay is not a solution.”
He added: “It is quite possible that our friends in the European Union will reject Parliament’s request for a further delay (or not take a decision quickly).”
The PM also discussed the situation with French President Emmanuel Macron on Saturday.
Amid noisy Commons scenes, Mr Johnson insisted that he was not “daunted or dismayed” by the vote result, and remained committed to taking Britain out by October 31.
“I will not negotiate a delay with the EU, neither does the law compel me to do so,” he said.
The SNP leader at Westminster Ian Blackford said that if Mr Johnson acted as if he was “above the law”, he would find himself in court.
Liberal Democrat leader Jo Swinson said: “The most urgent thing right now is the Prime Minister complies with the law.”
The Benn Act set a deadline of 11pm on Saturday for the Prime Minister to get a deal if the UK is to leave on October 31, otherwise he is supposed to seek an extension.
Commons Leader Jacob Rees-Mogg said the Government was planning to give MPs a fresh chance to have a “meaningful vote” on the deal hammered out by Mr Johnson with Brussels on Monday.
Speaker John Bercow said he would rule on Monday whether it was in order for the Government to hold the vote, after not pressing ahead with it on Saturday following its defeat on the Letwin amendment.
The voting took place as a mass protest converged on central London in a People’s Vote campaign march in support of a second referendum.
The Government was consigned to defeat after the 10 MPs of Mr Johnson’s erstwhile allies in the DUP joined the other opposition parties in voting for the amendment.
The party is furious about the proposed customs arrangements for Northern Ireland which would see checks on goods coming from the rest of the UK.
