Khan wants expansion at Gatwick to become official party policy, telling the Observer that the south-London airport was clearly the “only viable option”, and that further development at Heathrow would be “disastrous and undeliverable”.

The mayoral candidate reportedly called for a clear line from Labour after the party’s transport spokesperson appeared to sit on the fence following the government’s decision to again delay an announcement on where to expand airport capacity in the south-east.

Lilian Greenwood caused dismay among Labour MPs by insisting that the party could not take a view on whether to back Howard Davies’ recommendation to expand Heathrow, until the government had made its own position clear.

Khan has changed his view since deciding to run for the position of mayor. He said it was now time to ditch Heathrow and throw support behind Gatwick.

“Gatwick can expand without the devastating environmental impact of a third runway at Heathrow, while bringing huge economic benefits and being more affordable and deliverable,” said Khan.

“I’m calling on David Cameron, Zac Goldsmith and my colleagues in the Labour party – Jeremy Corbyn and John McDonnell – to get behind Gatwick now. It’s the only viable solution to this problem,” he added.