Greece is conducting "sensitive discussions" to secure the return of two 2,500-year-old frieze fragments from the Acropolis held in Italy and Germany, with talks focusing on which items might be offered in exchange, a culture ministry source said on Tuesday.

The two marble fragments removed from the Parthenon, the fifth-century BC temple atop the Athens Acropolis, are respectively held by the archaeology museum in Palermo, Italy, and by Heidelberg University in Germany.

The Greek authorities in 2003 offered a rare bronze helmet to the Palermo museum in exchange for a foot from a statue of an ancient Greek divinity.

The culture ministry has offered no explanation for the delay in making the exchange, but is nevertheless hopeful that the affair will be concluded during a scheduled visit to Rome later this month by Greek President Karolos Papoulias.

The second item in question is the heel of a male statue, which the culture ministry last week declared that Heidelberg University would return in 2006, though without referring to an item exchange.

"Officially, the university did not ask for anything in exchange, but Greece wants to make a goodwill gesture," a ministry source said on condition on anonymity, when asked to comment on related press reports.

The successful conclusion of these negotiations would enable the Greek government to increase pressure on the British Museum for the restitution of the Parthenon's eastern frieze, better known as the Parthenon Marbles.

Greece has spent over 20 years seeking the return of the temple frieze, which was removed in 1806 by agents of Lord Elgin, the British government's ambassador to the Ottoman Empire