Published: 8:26 AM October 26, 2018 Updated: 6:17 PM September 17, 2020

London mayor Sadiq Khan is to urge EU leaders to extend Article 50 and delay Brexit until a second referendum or a new government is formed.

He will tell the EU's chief negotiator Michel Barnier when they meet in Brussels today that an extension is in the interests of both sides to avert a "political and economic crisis".

Speaking ahead of the meeting, Khan said "what happens over the coming weeks and months will have an enormous impact on London, the UK and all of Europe for many decades to come".

He said: "It's now extremely likely that Parliament will vote down any bad deal negotiated by Theresa May, which means it will be in the best interests of both the UK and the EU to extend Article 50 in order to leave time for either a public vote or for a new government to reset the negotiations.

"London and Europe are inextricably linked. Europe's biggest businesses are huge investors in the UK economy, they depend heavily on the UK market and rely enormously on the strength of the City for financing.

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"London's success has been good for the UK and good for Europe.

"With so much at stake for both the UK and the EU - and with the British government heading towards a defeat in Parliament - I hope Michel Barnier and the EU will agree to start preparing now to extend Article 50 so that we can avert a political and economic crisis that could have enormous repercussions for all of Europe."

Khan's visit is the latest by a UK politician to Brussels for talks with Barnier as the two sides seek a workable Brexit Withdrawal Agreement.

He is also due to visit Paris, Berlin and Dublin before the end of the year to promote London ahead of Brexit.

While in Brussels he is also due to meet EU vice presidents Valdis Dombrovskis and Maros Sefcovic and EU commissioner Sir Julian King "to discuss London's needs from the Brexit negotiations".

London voted heavily in favour of Remain in the 2016 referendum.

On Saturday, Khan was among the politicians who attended a march by hundreds of thousands of people through the capital, thought to have been the biggest anti-Brexit demonstration since the referendum in 2016.

But his overt backing for the second vote on whether to quit the EU has put him at odds with the Labour leadership.

Various frontbenchers have insisted a second referendum should only happen if the government fails to get a Brexit deal through Parliament and refuses to call a general election, and none of the shadow cabinet attended Saturday's demonstration.