Armed robbers have seized dozens of items on display at the museum in Ancient Olympia, the birthplace of the Olympics in southern Greece, after tying up an employee.
Police and museum authorities did not have an immediate account of the items taken from smashed display cases in the raid early today.
Greece's culture minister Pavlos Geroulanos submitted his resignation after the robbery.
Sporting authorities are due to hold a ceremony at the museum on May 10 to light the Olympic flame for the London Games.