Greece has accused Lord Elgin of theft and does not recognise the British Museum as owner of the sculptures.
The Parthenon, which is on the Acropolis in Athens, was completed in the fifth century BC as a temple to the goddess Athena and its decorative friezes contain some of the greatest examples of ancient Greek sculpture.
The British Museum has always ruled out returning the parts in its collection, which include about half of the 160 metre (525 ft) frieze that adorned the Parthenon and maintains that they were acquired legally.