Egypt’s government claims British auction house Christie’s illegitimately acquired a 3,000-year-old bust representing ancient pharaoh Tutankhamun, which sold for £4.7 million on Thursday.

In June, Egyptian Minister of Antiquities Khaled Al Anani had convened a National Committee for Returning Stolen Artefacts to stop the sale.

His predecessor Zahi Hawass said the bust was likely stolen after 1970, when other artefacts vanished from Karnak temple—adding Christie’s lacks “ethics” and did not release documents proving “they took it legally.”

However, to demonstrate its right to sell, Christie’s published the bust’s recent ownership history, starting in the 1960s.

Tracing artworks which have spent generations in family collections is difficult, and fuels so-called “grey markets” for pieces neither explicitly looted nor totally traceable.

Some experts believe bitter arguments over antiquities’ origins could push sales further into private markets, undermining the efforts toward transparency of more established houses like Christie’s.

Christie’s affirms it respects “bilateral treaties and international laws” on “cultural property” and upholds “the highest standards for the transfer of objects.”

But Egypt has reignited the debate around colonial-era handling of heritage treasures, saying Christie’s sale may be legal—1983 law criminalising artefacts’ extraction from Egypt does not apply to the bust—but not moral.

Should historical artefacts belong to their traders, or their source countries?