(Reuters) -Uber ( UBER ) said it found more than 100 instances in which passengers who claimed its drivers sexually assaulted or harassed them offered bogus or doctored receipts to prove ridership, or did not explain their inability to provide receipts.

In a Wednesday court filing, Uber ( UBER ) urged U.S. District Judge Charles Breyer in San Francisco to order 21 plaintiffs with suspect receipts to justify why their claims should not be dismissed, and 90 plaintiffs to provide receipts or "non-boilerplate" reasons for their absence.

At least 11 law firms represent the various plaintiffs, court papers show. Those firms had no immediate comment or did not immediately respond to requests for comment on Thursday. They were not accused of wrongdoing.

Uber ( UBER ) is trying to reduce its liability in nationwide federal litigation comprising more than 2,450 lawsuits alleging driver misconduct. It faces several hundred additional lawsuits in San Francisco Superior Court.

The San Francisco-based company has maintained it should not be liable for criminal conduct by drivers it connects with passengers, and that its background checks and disclosures were sufficient.

On July 8, Breyer dismissed some fraud and liability claims that were based on ads promoting Uber's ( UBER ) ride-sharing service as a safe alternative to drunk driving.

In Wednesday's filing, Uber ( UBER ) said some fake receipts appear to have been generated through third-party websites.

Uber ( UBER ) said some receipts contained math errors or bogus surcharges, changed female driver names to male names, were timestamped before rides occurred, had stray marks, or used formatting that does not match its own.

One plaintiff submitted two receipts for a single ride, while two plaintiffs submitted different versions of the same receipt, the company said.

"Nothing is more critical to the integrity of our judicial system than honesty," Uber ( UBER ) said. "It is difficult to conceive an act of misconduct graver than the outright fabrication of evidence that plaintiffs here undertook."

The case is In re Uber Technologies Inc Passenger Sexual Assault Litigation, U.S. District Court, Northern District of California, No. 23-03084.