Turkey’s government has embarked on an aggressive campaign to repatriate ancient treasures displayed in some of the world’s great museums, claiming the items were looted from the country decades ago, writes The New York Times.

While Turkey has signed a widely accepted Unesco convention that allows musems to acquire artifacts that were outside their countries of origin before 1970, it is both citing a century-old Ottoman law and staking a moral claim in seeking returns from the Metropolitan Museum of Art, the Louvre, the Pergamon in Berlin, and other institutions.

“We only want back what is rightfully ours,” said Murat Suslu, an archaeologist and Turkey’s director-general of cultural heritage and museums. Turkey has refused to lend treasures and delayed approving archaeological excavations as part of the reclamation campaign.

Hermann Parzinger, president of the foundation that runs the Pergamon, accused Turkish officials of “engaging in polemics and nasty politics” and noted that Istanbul museums contain objects taken by the Ottoman Empire centuries ago when its domain stretched across the Middle East and into Europe.

Turkey’s effort, which magnifies similar campaigns by Greek and Italian officials, comes amid an increasingly rancorous debate among governments, museums, collectors, and researchers over whether treasures of the ancient world should be rightfully returned to their regions of origin.