Regulator Transport for London (TfL) shocked the Silicon Valley firm by rejecting its license renewal bid in September.

"While we haven't been asked to make any changes, we'd like to know what we can do," said Uber's general manager in London.

Transport for London says Uber, whose app is used by 3.5 million passengers and 40,000 drivers in the British capital, isn't "fit and proper" to hold a license to operate a private-hire vehicle service.