Sadiq Khan said he had been assured there was “no logical reason” why the Covid-19 outbreak should lead to the cancellation of the London mayoral election in May.

And, in contrast to his Independent rival Rory Stewart, the Labour London mayor backed the Prime Minister over his decision not to issue firmer social clampdowns, such as shutting schools, to prevent spread of the deadly virus.

Mr Khan, speaking on LBC radio, said the chief medical officer Professor Chris Whitty had briefed him to advise that the May 7 election would likely be able to take place.

“One of the questions I asked the chief medical officer was, is this election still going to take place?” said Mr Khan, who is vying for a second term at City Hall.

“His advice was quite clear.

“He said there is no logical reason to postpone or cancel the elections.”

Prof Whitty, according to Mr Khan, has recommended concerned voters switch to a postal vote and suggested ballot box pencils be washed regularly to ensure polling station voting can commence.

“If someone is worried about going to a polling station, it is really important to make postal votes as easy as possible,” the mayor continued.

“If there is a very small risk, the way to make that risk even smaller in relation to spreading the virus is wiping the pencils with individual wipes.

“You can always wash your hands after voting.

“And with some people on the ballot paper, some people might want to wash their hands after they’ve chosen to vote for that candidate,” he joked.

Mr Khan, who has been barred from attending the Covid-19 emergency Cobra meetings, came to the defence of Boris Johnson in his handling of the crisis, arguing that the Conservative Party leader had followed expert advice.

Former MP Mr Khan said: “I’m the first person to criticise Boris Johnson – for me, it is pleasure and business.

“I can’t fault the Prime Minister for following the advice of the chief scientific adviser (Sir Patrick Vallance) and the chief medical officer.

“There is motive for me to try and criticise Boris Johnson.

“Having a dividing line with a Conservative prime minister makes political sense.

“I ain’t gonna do it though, for that reason.”

His comments were in stark contrast to former international development secretary Mr Stewart’s stance.

The mayoral candidate has announced he has suspended his campaign, called for schools and Parliament to be shut and urged for the London marathon to be cancelled.

In a separate interview with LBC radio, Mr Stewart branded the Capital’s leader “completely irresponsible” for holding a mayor’s question time on Wednesday at Battersea Arts Centre, which has a capacity for 640 people.

Mr Khan admitted to being “scared” about the numbers of people who could die from coronavirus but vowed he “won’t keep Londoners in the dark” and would alert them to when advice on using public transport or attending large events would have to change.

The ex-minister said shutting schools when Mr Stewart first argued to two weeks ago could have “inadvertently made matters worse” by putting vulnerable grandparents more at risk if they had to step in and look after grandchildren while parents were continuing to work.

The 49-year-old, who has had a long running spat with Donald Trump, criticised the US president’s shock move to ban flights from Europe, bar from the UK and Ireland.

“I fear this is another example of policy on a whim rather than on evidence, so it is a bit odd,” he told LBC.