Washington, DC (CNN Business) The state of California revealed Wednesday it is investigating Facebook over the technology giant's privacy practices, complaining in a court filing that the company has failed to comply with multiple requests for information.

The investigation, which had not been previously disclosed, has been underway for more than a year. Its existence was confirmed Wednesday when California Attorney General Xavier Becerra, in a court filing, said Facebook should be forced to cooperate with the investigation.

"If Facebook had complied with our legitimate investigative requests, we would not be making this announcement today," Becerra said. "But our work must move forward."

In a statement, Will Castleberry, Facebook VP of state and local policy, said: "We have cooperated extensively with the State of California's investigation. To date we have provided thousands of pages of written responses and hundreds of thousands of documents."

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