London: Boris Johnson said he "will not" carry out the British Parliament's instructions to seek an Article 50 extension if he fails to agree a new Brexit deal by the deadline, adding he was only bound "in theory" by a law passed on Friday.

British Prime Minister Boris Johnson leads a bull around a pen as he visits Darnford Farm in Banchory near Aberdeen, Scotland, on Friday. Credit:Getty Images

The British Prime Minister has also ruled out resigning to avoid asking the European Union for an extension beyond October 31, saying he would stay in office to deliver Brexit and defeat Labour leader Jeremy Corbyn.

Failure to comply with the law could see Johnson taken to court, but Iain Duncan Smith, an MP and the former Tory leader, said the Prime Minister should be willing to be and would be seen as a Brexit "martyr".

The House of Lords passed the rebel bill on Friday without any amendments, meaning it will not need to return to the House of Commons and will instead be sent to the Queen for royal assent on Monday and likely become law before Parliament is suspended at the end of the last scheduled parliamentary session, on Tuesday.