SAN FRANCISCO (Reuters) - The U.S. Department of Justice sued California's corrections system on Thursday, saying prison supervisors failed to prevent a male cook from being sexually harassed by his female co-worker.

Joe Cummings started working as a cook in 2007 at a youth correctional facility in Chino, California, according to the lawsuit. The following year, another cook began to use sexual innuendos and repeatedly asked him "what it would take" for him to have sex with her, the suit says.

She later confronted him in a stairwell with her blouse unbuttoned and propositioned him. Cummings complained to his supervisors and despite an internal investigation the female cook was not disciplined, according to the suit.

The suit is the latest in a series of woes facing the California corrections system, whose state prisons are under court orders to reduce overcrowding and have been plagued by hunger strikes and occasional violence.