Boris Johnson has used a call with the UK’s directly elected mayors to urge them to keep cars out of city centres when the nation begins to emerge from lockdown.

Writing on Twitter this week, London’s cycling commissioner Will Norman said that with the capital’s public transport capacity greatly reduced when restrictions area eased, up to eight million journeys a day would need to be made by other means.

“If just a fraction switch to cars, London will grind to a halt, choking our economic recovery,” he said.

The situation will be similar in other major cities and Jamie Driscoll, the Labour mayor for the North of Tyne, told the Guardian that Johnson was therefore keen for people to cycle instead of drive when the lockdown is eventually lifted.

“It was very interesting that the Prime Minister was talking about taking the opportunity to push clean, green travel, active travel, cycling infrastructure and getting cars off the road,” said Driscoll.

“The real risk is that you end up with a situation where people go back to work in their cars, into city centres that are not designed to take that amount of traffic, that congestion makes it harder for buses to get through and you end up with this vicious cycle.

“We will be coming out of a crisis involving a virus that makes it very difficult for people to breathe. The last thing we need is a man-made equivalent.”

Greater Manchester’s cycling commissioner Chris Boardman has tweeted that he, Mayor Andy Burnham and the various boroughs are already “on the case” with regards to encouraging cycling when lockdown measures are relaxed and that plans will be announced next week.

Driscoll also mentioned that Johnson had made references to active travel and reducing obesity. He speculated that obesity’s association with increased risk of complications from Covid-19 may have played on the Prime Minister’s mind during his recent experience of the illness.

“Obesity is a massive issue and also a very expensive issue, because it does cause a lot of us, as we get older, to spend many years when we can’t be that active,” he said.

“It’s just speculation, and far be it from me to comment on the prime minister’s physique, but maybe having just been through it he has had a Damascene conversion.”

The Government has said it will set out a “comprehensive plan” next week on how to get the economy moving, reopen schools and help people travel to work following the coronavirus lockdown.

Dr Rachel Aldred, at the University of Westminster, said the coming weeks and months presented a potential tipping point with regards to improving urban transport. However, she warned that without appropriate action, cities could end up taking a step backwards.

“This is a really important moment,” she said. “There is the potential to lock in the reduction in air pollution we have seen over the past weeks if we get this right, but as people begin to go back to work and can’t or don’t feel safe using public transport, there is the potential to instead lock in a huge increase in car use and pollution.”

Mark Watts, the chief executive of C40 Cities – a network of 96 cities around the world collaborating to address climate change – said: “There is now a hell of a lot of collaboration among very powerful politicians who do think a green economic recovery is absolutely essential.”

Watts expressed optimism that short term measures could endure. “This is how cities are going to function for the next two years, and probably that will transition – if we have a green economic recovery – into permanence.”