WASHINGTON » The Army is investigating how 9-foot-tall, decorative marble urns that once flanked the stage of Arlington National Cemetery’s Memorial Amphitheater ended up on a private auction block.

An Alexandria auction house is planning to sell two decorative urns and 14 marble balusters that once stood in the amphitheater next to the Tomb of the Unknown Soldier.

The urns were apparently removed from the cemetery during a 1990s renovation. Since 1997 they have been at a Maryland antiques shop, but the shop owner is closing the store and auctioning its inventory. He says he bought the urns from the company that renovated the amphitheater, replaced the urns and took away the originals.

After learning of the sale from The Washington Post, the Army on Friday asked The Potomack Company to halt the urns’ auction.