Culture Minister Pavlos Geroulanos offered to resign, but his departure from the cabinet was not expected to destabilise the government, which is rushing to clinch an international bailout to ease the country's debt crisis.

Police said armed thieves had broken into the one of the two museums at Olympia in southern Greece, overpowered a female security guard and stole some 70 bronze and pottery objects.

"They overwhelmed and gagged the woman who guarded the building," a police official told Reuters.

"The value of the objects stolen has not been estimated yet."

In January, three works of art, including one by Pablo Picasso and another by Dutch painter Piet Mondrian, were stolen from the country's National Gallery in the capital, Athens.

After the first gallery robbery, culture ministry officials said cuts to museum budgets had damaged security arrangements.

Greece has seen a rise in crime as its debt-laden economy has shrunk 16 percent in size from its 2008 peak, leading to youth unemployment of just under 50 percent.

A government spokesman said Prime Minister Lucas Papademos would decide whether to accept the resignation once all the facts were clear.

(Additional reporting by Renee Maltezou; editing by Matt Robinson and Paul Casciato)

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