Uber said on Monday that it was not clear what concerns London’s transport regulator had for stripping it of its license as the taxi app battles to keep operating in one of the world’s wealthiest cities.

On Friday, the British capital’s regulator deemed Uber unfit to run a taxi service and decided not to renew its license to operate, which will end this week.

It cited the firm’s approach to reporting serious criminal offences and background checks on drivers.

“Sitting down with Transport for London (TfL) representatives as soon as possible would be the most helpful thing to really understand their concerns to work out what they are,” Uber’s UK Head of Cities Fred Jones told Media.