Greek police said on Tuesday they were holding three men in connection with an attempt to sell an antique statuette from a Syrian site.
Two Syrian immigrants and a Greek national were detained in Athens on Monday following a sting operation by a police unit combating illegal dealings in antiquities which had been tipped off.
An officer posing as a potential buyer agreed a price of 120,000 euros (158,000 dollars) for the bronze statuette of a lion, said by experts to date from the 4th century BC and measuring 25 by 10 centimetres (10 by four inches).
The two Syrians, aged 45 and 32 and living illegally in Greece, said the statuette came from illegal excavations in their country, the head of the unit Dimitris Pitikakis told AFP.
It is unusual for foreign antiquities to be seized in Greece, even though the illegal traffic has intensified in recent years with the arrival of tens of thousands of immigrants, in particular from Iraq and Afghanistan, he said.
To protect its own heritage Greece passed tougher legislation last year against trafficking, with rewards paid to informers.