HOUSTON, July 13 (Reuters) - A U.S. judge set bond for James Davis, the ex-chief financial officer of offshore bank Stanford International Bank Ltd, at $500,000 on Monday.

The bank's founder, R. Allen Stanford, has been ordered held without bail until he can stand trial in an alleged Ponzi scheme that federal prosecutors claimed bilked clients of billions of dollars.

Davis, who is cooperating with federal prosecutors, appeared before U.S. Magistrate Judge Calvin Botley in federal court in Houston.

Davis faces conspiracy and obstruction charges related to a $7 billion scheme involving certificates of deposit issued by the offshore bank in Antigua. (Reporting by Anna Driver in Houston; Editing by Lisa Von Ahn)