A US federal judge referred embattled tech giant Uber to the Justice Department over allegations of corporate theft against a Google-affiliated company.

District Judge William Alsup in San Francisco requested the criminal justice review late Thursday "for investigation of possible theft of trade secrets."

Alsup said he made the decision "based on the evidentiary record," but "takes no position on whether a prosecution is warranted."

Self-driving car firm Waymo sued Uber over the alleged theft of more than 14,000 confidential files by former Waymo employee Anthony Levandowski before he left the company.

Levandowski co-founded self-driving truck startup Otto that Uber later acquired for a reported US $680 million (620 million euros). Waymo alleged that Uber's Lidar system, a vital sensor technology, was fast-tracked using information from the plundered documents.

Uber denied using Waymo's ideas, saying its Lidar system used different technology. Levandowski refused to hand over his laptop or answer most questions posed by Waymo's lawyers, asserting his Fifth Amendment right against self-incrimination.

Judge Alsup also denied Uber's request to force the two parties into mediation and avoid the civil trial. He partially filled Waymo's request for an injunction - filed under seal - which could prevent Uber from deploying the technology.

The moves came after a bad year for Uber which was besieged by sexual harassment and sexism claims, Chief Executive Travis Kalanick yelling at an Uber driver on camera, and revelations that the company developed a secret weapon to thwart authorities.

aw/kms (AFP, AP, Reuters)