LONDON (REUTERS) - The London transport regulator's decision to strip Uber of its licence to operate in the capital was "disproportionate" and has put thousands of jobs at risk, British Prime Minister Theresa May has told the BBC.

Regulator Transport for London (TfL) last Friday deemed Uber unfit to run a taxi service and decided not to renew its licence to operate when it expires on Sept 30, citing the firm's approach to reporting serious criminal offences and background checks on drivers.

"Yes there are safety concerns and issues for Uber to address, but what I want to see is a level playing field between the private firms and our wonderful London taxis, our black cabs, our great national institution," May said in her interview with the BBC.

"I want to see a level playing field. I think a blanket ban is disproportionate," she said.

Chief executive Dara Khosrowshahi, who is less than a month into his new job, has apologised to Londoners for the taxi app's mistakes and said Uber will appeal against the decision.

The Silicon valley firm will be allowed to operate in London until the licence appeal process is exhausted, which could take several months.

"At a stroke of a pen, what the mayor has done is risked 40,000 jobs and of course... damaged the lives of those 3.5 million Uber users," May said in the interview, given before the start of her Conservative Party's annual conference on Sunday.

London Mayor Sadiq Khan, a politician from the national opposition Labour Party who has criticised the firm in the past, said on Monday he had asked TfL to be available to meet CEO Khosrowshahi.

The ride-hailing service has faced regulatory and legal setbacks around the world amid opposition from traditional taxi services and concern among some regulators.

It has been forced to quit several countries, such as Denmark and Hungary.

Uber is separately defending its business model in Britain and told a tribunal on Wednesday its drivers were self-employed, not workers entitled to a range of benefits.