Fight on: Boris Johnson set to go head-to-head with Uber exec Jo Bertram

Johnson is calling for new legislation that would limit the number of mini cabs in the city but Uber sees the proposals, set to be officially unveiled in this month's Queen's speech, as a direct attempt to derail its success in the city.

Uber UK chief Jo Bertram has requested the opportunity to debate the matter with Johnson in person, according to a letter seen by the Financial Times.

She claims the move will lead to higher prices for the millions of travellers that visit the capital every year.

"London is one of the great cities of the world and Londoners have embraced Uber's technology; tens of thousands rely on us for their job and millions more use us to get where they need to go," Bertram writes in the letter.

"Capping the industry's ability to grow would mean higher prices and less availability for the millions of people who rely on Uber and services like ours to get around."

Bertram also hit out against the fact that Uber is not yet represented on the board of Transport for London and other industry bodies from which it would be able to better challenge the plans. Indeed, Bertram told Techworld in March that she's currently in a standoff with the UK government over what role it plays in the so-called sharing economy and whether it should be a part of the Sharing Economy UK trade body.

Bertram also argues that new regulations should "protect people their personal safety and their pockets not hamper new innovations they value and that make their lives easier".

A spokesman for Johnson said: "The Mayor is not on an Uber witch hunt...It doesn't matter who the drivers work for. It just doesn't make sense to have such a large number of minicab drivers in the capital.

"We must be able to take action against the threat posed by the massive increase we are seeing in the number of private hire vehicles," he added.

Johnson said the surge in minicabs are having a detrimental impact on the capital's congestion, air pollution and the issue of illegally parked cars.

Minicabs now account for 78,000 of the vehicles in London, with Uber making up about 14,000 of those.

The rise in minicabs and services like Uber and Hailo has put a strain on the black cab industry, leading to protests in Central London.

The transport regulator is currently undertaking a review of the London taxi market.