Scores of silver coins dating back well over two millennia have been unearthed in the heart of Athens, officials announced Thursday.

More than five kilos (11 pounds) of silver pieces dating primarily from the 4th century BC were discovered in an excavation project of the American School of Archeology, a statement from the ministry of culture said.

Some 45 of the silver pieces are believed to date back to the 5th century BC.

The discovery at the Athens Agora - the chief marketplace and ancient center of the city's civic life - is of "considerable importance" because it represents one of the most sizable finds of its kind, the statement said.

The new discovery will be "an important and useful source of information about the money of antiquity and the economic life of the times," the text said.

The total number of coins uncovered has yet to be specified.

The Agora, situated at the foot of the Acropolis, is one of the most important excavation sites in the Greek capital.