SAN FRANCISCO » San Francisco lawyers have filed a lawsuit against Costco, claiming that the retail giant sells shrimp produced by slave labor in Thailand.

The San Francisco Chronicle reports the lawsuit filed Wednesday seeks to end the imports and demands refunds for its California customers.

Thailand-based CP Foods, which supplies Costco with the shrimp, is also named in the lawsuit for allegedly using fish hauled by unpaid migrant workers to feed the shrimp.

The lawsuit claims that the unpaid laborers, many of them Burmese, work 20-hour days, seven days a week. Former slave laborers have reported being whipped and electrically shocked.

No one at Costco was available for comment.

A lawyer for the plaintiffs says the shrimp are also being sold by other U.S. companies, and more suits may follow.