British Prime Minister Boris Johnson's reasons for suspending parliament in the final weeks before Brexit "cannot be true", a lawyer for former premier John Major told the Supreme Court on Thursday.
Major, who is from Johnson's Conservative party, believes the prime minister was acting entirely in his own political interests to avoid scrutiny by MPs as Brexit comes to the crunch, with Britain due to leave the EU on October 31, the lawyer said.
The Supreme Court is hearing the last of three days of highly-charged arguments over whether Johnson's advice to Queen Elizabeth II to prorogue, or suspend, parliament for five weeks until October 14 was lawful.
Johnson, who took office in July, insists it was a routine move to allow his government to launch a new legislative programme next month.
But it sparked legal action accusing him of trying to silence MPs, who oppose his threat of leaving the EU next month with no deal.
In a dramatic attack by one former Conservative leader on another, Major alleged "the reasons set out in the documents put before the court by the prime minister cannot be true," his lawyer
The lawyer added: "It would be very straightforward for the prime minister or a senior official to sign a witness statement confirming (for example) that the decision had nothing to do with Brexit if that were indeed the case, and despite repeated requests nobody has been prepared to do so."
"We are not concerned with when and how and on what terms the UK leaves the European Union."