Waymo, Alphabet's self-driving-car division spun off from Google, has asked a federal judge to block Uber's self-driving-car project, accusing the ride-hailing service of using stolen intellectual property to operate its self-driving vehicles.

The preliminary injunction, filed in federal court on Friday, comes a few weeks after Waymo filed an explosive lawsuit accusing Uber of stealing the design for its lidar sensor that allows the car to detect obstacles. The injunction asks Uber to stop making and using the devices it claims were stolen.

Waymo filed a sworn testimony by Gary Brown, a forensic-security engineer, who said Anthony Levandowski, a former employee, had downloaded 14,000 highly confidential and proprietary files relating to Waymo's self-driving-car project.

Levandowski is an original member of Google's self-driving-car unit. He left after nine years to found Otto, a startup focused on autonomous trucks, which was acquired by Uber last year.

Brown claims that Levandowski downloaded the files in December 2015 before leaving the company in January.

Brown accused Radu Raduta, a former Google mechanical engineer, and Sameer Kshirsagar, the former global supply manager for self-driving cars, of downloading other confidential material before joining Levandowski at Otto.

Uber has denied the allegations made by Waymo in the lawsuit, calling them "a baseless attempt to slow down a competitor." Uber did not immediately return Business Insider's request for comment on the injunction filed Friday.

This post originally appeared on Business Insider.