Uber Technologies on Friday said that its self-driving sensor technology was different from Waymo's, responding to Google's unit's claim that it profited from stolen files.

Waymo sued Uber in February, seeking a preliminary injunction to stop it from using trade secrets and other intellectual property at the center of the case. Waymo claims that its former executive, Anthony Levandowski, stole computer files before joining Uber as a leader to the company's self-driving program. Uber said in a federal court filing that Waymo's computer files never ended up on its servers.

"The record shows that Uber never possessed - and never used - any information Mr. Levandowski allegedly took from Waymo," Uber wrote in its filing.

Levandowski has not handed over the allegedly stolen documents and Uber, which has never denied that Levandowski took the files, claims it cannot force him to do so.

U.S. District Judge William Alsup in San Francisco has ordered Uber to do a more "thorough search of its computer systems".

"If you cannot find them in your files there is going to be a preliminary injunction. You're not denying it, no one is denying he has the 14,000 files," Alsup said.