PARIS (Reuters) – French auction house Millon denied accusations by the Mexican government that a sale of dozens of pre-Columbian artefacts was illegal and proceeded with an auction on Wednesday.

Mexico’s foreign ministry on Tuesday said that 95 of the 120 pieces on auction appear to be from Mexican cultures, including the emblematic pre-Columbian city of Teotihuacan, as well as the Olmeca and Maya cultures.

Millon president Alexandre Millon told Reuters on Wednesday that Manichak and Jean Aurance, listed as the owners of the artefacts, satisfied all the legal criteria to justify their ownership of the collection, which they amassed after falling in love with a piece in a Paris gallery in 1963.

“The problem for Mexico is that this collection is exemplary in every way: provenance, publications and exhibitions it has featured in. That should make it a positive platform for Mexico”, Millon, said ahead of the auction.

The collection includes sculptures, masks and religious artefacts from before 1000 BC up to the 18th Century A.D.

“(The Mexican government) should use this auction to say ‘Look at this sale, it’s ones like these that we need’ in an effort to stop other auctions which might not take the same precautions”, Millon continued.

The tensions over the pre-Columbian art pieces come amid a wider discussion over whether Western collectors and museums should return objects to their countries of origin. Collectors and museums often argue that there they lack adequate care.

French President Emmanuel Macron last year became the first Western leader to initiate a comprehensive review of artefacts looted during colonial times and promised to return 26 pieces to Benin.

Mexico’s ambassador to France Juan Manuel Gomez-Robledo said, “Mexico is the rightful owner of these artworks and we’ve come here to express our unhappiness and to explain why this violates not only Mexican law but also international law.”

(Reporting by Antony Paone and Michaela Cabrera; Writing by Benoit Van Overstraeten; Editing by Richard Lough and Alexandra Hudson)