Boris Johnson would rather defy the law than ask for another Brexit delay, he has indicated, as Labour was accused of plunging Britain into a constitutional crisis.

The Prime Minister said he “will not” carry out Parliament’s instructions to seek an Article 50 extension if he fails to agree a new deal, adding he was only bound “in theory” by a law passed on Friday.

Mr Johnson also ruled out the option of resigning to avoid asking for an extension, saying he would be staying in office to deliver Brexit and defeat Jeremy Corbyn.

On Monday the Prime Minister will make a second attempt to win the backing of MPs for an election on Oct 15, in which he would hope to win a fresh mandate for leading the country out of the EU on Oct 31 with or without a deal.

But Labour, which fears it will lose an early election, is now in talks with other opposition party leaders about delaying a general election until the end of November, in the hope it can trap Mr Johnson into having to delay Brexit. SNP Westminster leader Ian Blackford boasted that the Prime Minister was now his “prisoner”.