Uber is to challenge London mayor Boris Johnson's plans to limit the number of minicabs operating in the capital Reuters

Uber is to challenge London mayor Boris Johnson's plans to limit the number of minicabs operating in the capital, warning the move would result in higher prices for users.

The retaliation comes in response to proposals by Johnson to limit how many minicabs can operate in London. The proposal is expected to feature in the next Queen's Speech on 27 May and is seen by Uber as a direct attempt to curb its successful business.

A letter sent by Uber's head of business in the UK, Jo Bertram, requests the chance to debate the issue with Johnson directly. Bertram claims the mayor's plans would "hamper new innovations [which] make [Londoner's] lives easier."

Seen by the Financial Times, the letter also points out that Uber is not yet represented on the board of Transport for London and has been excluded from other transport industry bodies.

Bertram added: "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...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."

As part of his proposals, Johnson said: "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."

The number of minicabs operating in London has increased by 20% in the past year to almost 80,000. Of these, 14,000 are operated by Uber drivers. Uber, which is a smartphone application connecting customers who need a lift with drivers who are nearby - and handles all payments automatically, so no cash is involved - is the largest private hire company in London.

But a spokesperson for the London mayor denied he "was 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."

London's black cab drivers have been angered by Uber, which often charges less and is subject to less regulation. Its drivers can also operate without passing the famous 'Knowledge' test, which black cab drivers must complete to prove they know every street in London without resorting to a map or sat-nav.

The London Taxi Drivers Association has previously taken legal action against Uber, claiming their drivers' use of smartphones to log journey's is in breach of taxi driver regulations.