SAN FRANCISCO, Sept 6 (Reuters) - Facebook Inc has turned over information about U.S. election ads it believes were bought by Russians to Robert Mueller, the special counsel in charge of investigating alleged Russian interference in last year’s election, a source familiar with the matter said on Wednesday.

The information produced by Facebook included copies of advertisements and data about the buyers of the ads, the source said. (Reporting by Joseph Menn; Writing by David Ingram; Editing by Sandra Maler)