Uber Technologies Inc. is accustomed to getting sued. Now it's doing the suing, and it's partly thanks to Breitbart News.

The global ride-hailing company is taking advertising agency Fetch Media Ltd. to court for click fraud, alleging that the firm improperly billed Uber for "fake" online ads and took credit for app downloads it had nothing to do with. Fetch is owned by the world's fourth-largest advertising company, Japan's Dentsu Inc.

Uber filed the lawsuit Monday afternoon at the U.S. District Court in San Francisco. The company said it discovered something was amiss when it canceled a campaign on the conservative website Breitbart, where Fetch was placing Uber ads. As part of the lawsuit, Uber plans to seek at least $40 million in damages, according to people familiar with the matter who asked not to be identified disclosing legal plans. Fetch didn't immediately respond to requests for comment.