Black cabs protest London transport regulator Transport for London (TfL). Guy Bell/REX Shutterstock

There's a real risk Uber won't be allowed to operate in London, with the city's transport authorities spooked by the firm's history of poor behaviour.

Three board members at London's transport regulator, Transport for London, want Uber's operator licence cancelled, or renewed only with strict conditions, according to The Sunday Times.

They are particularly worried about Uber's corporate behaviour, predominantly in the US where the firm is being investigated by the FBI for using secret software to evade local regulators.

A leaked letter that TfL board member Michael Liebrich sent questions Uber's alleged "regulatory evasion", its passenger safety record, and the way it rates passengers.

The newspaper quotes a second board member as saying: "My position is that we shouldn't renew the licence. I did raise concerns about the way Uber reportedly 'games' its application to deceive regulators, also issues around increasing congestion and private hire vehicle numbers."

Transport for London is responsible for licensing black cab and private-hire drivers, as well as private-hire operators like Uber.

It's under serious pressure either to revoke Uber's licence or to impose serious restrictions on the company when the firm's licence comes up for renewal at the end of September.

Former Uber drivers, black cab firms, the police, and MPs have all been hugely critical of the firm over the last two years, claiming that drivers end up out-of-pocket, and that Uber fails to adequately report sexual assault. They argue that Uber has unfairly wriggled around existing rules and regulation to the detriment of London's traditional black taxis.

Uber's licence actually came up for renewal earlier this year, and TfL granted the company a four-month licence. In the meantime, it launched a consultation on whether to hike up the fees for a private-hire operator licence.

That means that even if Uber wins a five-year licence, it could end up paying more than £2 million for its 40,000 drivers in the city.

Uber said in an emailed statement to Business Insider: "Over 3 million Londoners regularly use Uber to get a reliable ride at the touch of a button and more than 40,000 licensed private hire drivers use our app to make money. Uber has been helping Londoners get around town and connect with public transport for over 5 years, and we want to continue to do so."