Britain’s soldiers seized thousands of metal castings and sculptures in 1897 during a raid on the Kingdom of Benin, then separate from British-ruled Nigeria.

The “bronzes” – actually copper alloy relief sculptures, many showing court figures – were auctioned off and then spread among institutions from New Zealand to Germany and the United States, with the biggest collection in London.

“In addition to maximum transparency, we primarily aim for substantial restitution,” German Culture Minister Monika Gruetters said in a joint statement issued with the foreign ministry and German museums late on Thursday.

“We want to contribute to a common understanding and reconciliation with the descendants of the people who were robbed of their cultural treasures during the times of colonialism,” Gruetters added.

The Ethnologisches Museum in Berlin has more than 500 historical artefacts from the Kingdom of Benin in its collections, mostly bronzes.

The University of Aberdeen in Scotland said last month it would return a Benin Bronze to Nigeria within weeks, one of the first public institutions to do so.

The British Museum, which holds hundreds of the sculptures, has alongside several other museums formed a Benin Dialogue Group to discuss displaying them in Benin City, some officially on loan.

Plans are underway in Nigeria’s Edo state, of which Benin City is the capital, to build a centre to store and study the returned artefacts by the end of 2021, and a permanent museum by 2025.

The German ministries issued their statement in conjunction with German museums that are part of the Benin Dialogue Group.

(Reporting by Maria Sheahan Editing by Gareth Jones)