App-based global taxi service Uber sued over fatal California crash

The family of a young girl killed by a driver affiliated with Uber, a fast-growing global app-based taxi service, has sued the company, adding to its growing list of legal problems.

On New Year's Eve, Sofia Liu, six, died after she, her younger brother and mother were hit by a car on a pedestrian crossing in San Francisco.

At the time of the crash, driver Syed Muzzafar was logged on to the Uber X smartphone app and was waiting for customers, the lawsuit, filed on Monday, said.

Uber said after the tragedy that it did not involve a vehicle "doing a trip on the Uber system" and that Uber had "deactivated" the driver's account. The company declined further comment on the lawsuit.

Uber lets people summon rides at the touch of a smartphone button and has entered more than 60 markets, ranging from its home city of San Francisco to Berlin and Tokyo.

Leaked information last month indicated the company, which began connecting passengers with drivers about three years ago, is generating US$200 million a year in revenue beyond what it pays drivers. But mounting legal troubles and discontent among some drivers appear to match the fast growth.

On Monday afternoon, a handful of drivers gathered outside Uber's San Francisco headquarters to protest against its tipping policy and other issues.