London's taxi regulator is revoking Uber's license to operate in the city, the agency announced on its Twitter feed on Friday morning. "Uber's approach and conduct demonstrate a lack of corporate responsibility," Transport for London wrote.

The agency cited Uber's "approach to reporting serious criminal offenses" as one problem with the company's conduct. It also pointed to Greyball, a controversial software program Uber allegedly used to mislead regulators about the locations of its cars, making it more difficult for regulators to ticket Uber vehicles.

Uber's license expires on September 30. However, it has 21 days to appeal the agency's ruling, and it can continue operating in the city during the appeal process.

London's Licensed Taxi Drivers Association praised the decision. “Since it first came onto our streets Uber has broken the law, exploited its drivers and refused to take responsibility for the safety of passengers,” a spokesman told the Independent.

Uber's London manager vowed to challenge the decision, arguing that it would hurt 40,000 Uber drivers in the city. "To defend the livelihoods of all those drivers, and the consumer choice of millions of Londoners who use our app, we intend to immediately challenge this in the courts," he said.

In the last couple of years Uber has had an acrimonious relationship with regulators across Europe. Two years ago, French regulators arrested two Uber executives, and Uber was fined in France last year for running an illegal transport service. Uber also briefly faced a ban in Italy that was reversed by courts in May.

Uber has faced bans in Germany and Spain but was able to return to both countries after agreeing to employ licensed taxi drivers.