epa01433195 Detail of the exibition 'Spain, crossroad of civilisations' at National Anthropology Museum in Mexico City, Mexico, 06 August 2008. The exibition will be opened to the public on 12 August with the goal of making a historical review of Spain, with 239 pieces of artefacts from the Spanish National Anthropology Museum on display. EPA/ALEX CRUZ By Raul Cortes
Mexico has launched "appropriate legal proceedings before the relevant authorities" and reached out through diplomatic channels so the artifacts can be repatriated, Culture Secretary Claudia Curiel said in a post on the social media platform X.
"The defense of cultural heritage is a responsibility of the state and an act of historical justice," she said in the post.
Millon is scheduled to hold the in-person auction of a pre-Colombian collection called "Les Empires de Lumiere" (The Empires of Light) in Paris on Friday, according to Curiel.
Millon did not immediately respond to Reuters' request for comment. The auction house's website on Thursday displayed a message indicating it was undergoing maintenance.
Curiel shared a letter to Millon dated Tuesday, in which she wrote that Mexico's anthropology institute INAH had determined that 40 of the artifacts advertised by the auction house are protected by Mexican law.
"These goods are property of the Nation, unalienable and incontrovertible, and their export has been banned since 1827, and as such their presence outside the national territory derives from an illicit extraction," she wrote in the letter.
Mexico has for years sought to recover artifacts that make up its pre-colonial historical heritage from private collections around the world. Though some governments have agreed to repatriations, many remain the subject of extended disputes.
Among these is the iconic bejeweled headdress said to have belonged to Aztec emperor Moctezuma before he was toppled by Spanish conquistador Hernan Cortes.
Austria's Weltmuseum that houses the headdress has said that transporting it would damage its delicate, iridescent green quetzal feathers.
In 2023, Mexico's government launched a separate legal action against Millon over 83 objects it put up for sale that it determined were part of its cultural heritage.
At the time, Millon told trade outlet ARTnews it would move ahead with the sale, saying all its lots had "irreproachable origin" and conformed to criteria fixed by French law and the United Nation's cultural agency, UNESCO.
(Reporting by Raul Cortes; Writing by Sarah Morland; Editing by David Gregorio)