Mayor of Lindon Boris Johnson has been defended after he was caught on film telling a black cab driver to "f*** off and die".

In a video obtained by the Sun and Daily Mail, the Mayor and MP is seen riding his bike and being heckled by the cabbie.

The spat was apparently over Mr Johnson's policy on minicab booking service Uber, which has led to several protests from London taxi drivers.

In the 10-second video, captured by a bystander, the taxi driver can be seen leaning out of his window and shouting: "You are one of them mate, that's what you are. One of them."

The recently-elected Conservative MP then replies: "Why don't you f*** off and die - and not in that order."

As he drives away, the cab driver shouts: "Yeah b******s, hope you die."

The incident reportedly took place as Mr Johnson was cycling home on June 5 at around 12.20am in St John's Street, Islington.

A source close to the Mayor told the Mail: "I believe this particular cabbie is a serial heckler. He offered Boris a few choice words. Boris felt obliged to offer him a few in return. And off they went."

Boris Johnson defended after cabbie row

Mr Johnson's office has leapt to his defence over the F-word exchange, calling him "one of the black taxi trade's biggest champions".

a spokesman for Mr Johnson said: "He is determined to protect the livelihoods of cabbies, who are ambassadors for this great city and provide a gold standard service.

"The Mayor is not empowered to limit the number of private hire vehicles in London and that's precisely why he is pushing hard for parliamentary legislation that would give him the tools to do so."

The spokesman added: "Far from standing back from the pressing issues that the trade faces, the Mayor has taken action on a number of fronts, from stepping up minicab enforcement activity and launching a major review of minicab regulations, to seeking the mandatory use of card payments in all 25,000 black cabs to help boost business."

Previously, Mr Johnson said he understood the "unfairness and anger" felt by the black cab drivers, adding that there was "nothing he would like to do more" than ban Uber, but it would be very difficult to do so.

He added that he was upset that black-cab business appeared to be suffering but that it was "very difficult to fight a huge change in consumer preference".

Mr Johnson added: "You've also got to face the desire of millions of people in London to travel more cheaply."

London black cab drivers wants courts to sort out Uber 'problem'

A Licensed Taxi Drivers Association spokesman said: "I don't know know if this row involving Boris Johnson was over Uber, but the problem of Uber is really something that the courts need to sort out."

He went on: "The taxi trade believes that the regulations are being flouted. Boris says that there's nothing he can do about it but legislation never envisaged the arrival of technology so someone can just hire a cab at the push of a button.

"There have been calls for further protests by cabbies in London but I don't know if they are going to take place."

Angry cabbies have taken part in protests at what they see as an un-level playing field. They claim that Uber is opting out of the UK tax regime - something Uber denies - and is not subject to the same stringent restrictions as they are.

Labour's London Assembly transport spokesperson Val Shawcross to say: "The Mayor has the power to put in place a strategy to tackle the challenges facing the industry.

"But so far he's completely failed to respond to any of our calls to do just that."