Alphabet's Waymo claimed in a lawsuit earlier this year that Anthony Levandowski downloaded more than 14,000 confidential files before leaving to set up a self-driving truck company, which Uber acquired soon after.

Uber has fired Levandowski. He is not a defendant in the case, but his actions, and what Uber executives knew about them, are at the center of Waymo's lawsuit. Uber denies it used any of Waymo's trade secrets. A trial is scheduled for October.

In a court filing on Wednesday, Uber said Levandowski's downloads had nothing to do with his future employment at Uber.

"This is consistent with the complete lack of evidence that such files exist at, or have ever been used by, Uber," the company said.

Instead, Uber said it believes Levandowski took the files to ensure an expected $120 million (92.78 million pounds) bonus payment from Waymo. Uber did not detail how it believes the downloads would have helped Levandowski accomplish that objective.

At one point while Uber was negotiating to buy Levandowski's company, Levandowski told Uber executives including former CEO Travis Kalanick that he found five discs in his home that contained Google information.

"Kalanick emphatically told Levandowski that Uber did not want any such information," Uber said in the court filing, adding Levandowski said he destroyed the discs.

In a separate court filing, Waymo said the incident with the discs proved Uber executives knew he possessed Google information before he came to Uber.

"And even after finding out that he had Waymo materials in his possession...Uber never took any steps to prohibit Levandowski from using his 'treasure trove of files' in his work at Uber," Waymo said.

Waymo also said it has not been able to review all the correspondence Levandowski had with Uber executives. For instance, Waymo said it could not find text messages from Kalanick to Levandowski even though it did find messages from Levandowski to Kalanick, "suggesting that the former were deleted."

Uber had hoped Levandowski, one the most respected self-driving engineers in Silicon Valley, would help the ride services company catch up to rivals including Waymo, in the race for self-driving technology.

(Reporting by Dan Levine; Editing by David Gregorio)

By Dan Levine