One of the opposition Labour Party's senior members, Khan joins a growing list of politicians in favor of a second vote on EU membership. His call comes amid a deepening split over the government's Brexit proposals.
Almost six months before Britain is due to leave the European Union, London Mayor Sadiq Khan has called for a second referendum on the country's membership of the bloc.
Writing in The Observer newspaper, Khan said British Prime Minister Theresa May's government looked "unprepared and out of its depth" in negotiations with Brussels on its future relationship with the EU.
"This means a public vote on any Brexit deal obtained by the government, or a vote on a 'no-deal' Brexit if one is not secured, alongside the option of staying in the EU," he wrote.
He added the threat to living standards, the economy and jobs was too great for voters not to have a say.
'No mandate to gamble'
"I don't believe May has the mandate to gamble so flagrantly with the economy and people's livelihoods," said Khan, a member of the opposition Labour Party who campaigned for remaining in the EU ahead of the June 2016 referendum.
Known as the "People's Vote," the second vote idea is gaining traction among some politicians, unions and business leaders who argue that the public should effectively get a say on the final negotiated deal.
Khan has no direct role to play in the Brexit process, but he is a very influential member of the political class.
A great deal of uncertainty remains about whether London and Brussels will be able to agree a new trade and relations deal, or whether Britain will crash out in a chaotic manner.
Britain is set to leave the EU on March 29, but May's Brexit plans have still not been accepted and infighting within her ruling Conservatives is threatening to bring down her leadership.
Her former foreign secretary, Boris Johnson, is rumored to be plotting to oust her.
May admitted in a BBC interview to be broadcast on Monday that she gets "irritated" by the debate over her leadership during the difficult negotiations.
Johnson, who resigned in July to protest her plan to keep some close ties to the EU after Brexit, has compared her strategy to a "suicide vest."
"I have to say that that choice of language is completely inappropriate," May responded in the interview.
Johnson is among many influential Conservative figures who insist Britain should make more of a complete break from the EU than she is advocating.
mm/jm (AFP, dpa, Reuters)