A German far-right party has set its sights on blocking the return of the Benin Bronzes to their original African home.
Berlin promised last year to hand back more than 1,100 artefacts looted from the former Kingdom of Benin, now in Nigeria, in 1897 and displayed in German museums.
British collections have announced similar plans, but doubts have been raised after custody of the bronzes was from Nigeria's president to the Oba of Benin, a traditional ruler.
Germany said last month it was seeking clarity on whether the bronzes would still be displayed in a new museum, but said the plan to give them to Nigeria had not changed.
The Alternative for Germany (AfD) party has lodged a demand that the returns be stopped because Nigeria has "violated the spirit" of the agreement, parliamentary documents show.
The party is also calling for Germany to stop funding the planned Edo Museum of West African Art in Benin City, where it was envisaged that some of the bronzes would be housed.
"The government's restitution policy with regard to the Benin Bronzes ... is on the wrong track and must be ended before more irretrievable cultural goods are given away without conditions," a draft motion says.
The AfD, which is enjoying record support in the polls, is known for ruffling feathers by calling for Germany to take more pride in its history instead of focusing on remorse for the Second World War.
Germany's colonial history is less often discussed but it formally apologised in 2021 for atrocities in Namibia, a former imperial possession.
The 1,100 items from Nigeria were acquired by German collections and museums after the bronzes were looted by British forces during the capture of Benin City in 1897.
A symbolic first batch of 20 bronzes was given to Nigeria in December. It is intended that some items will be returned to Nigerian ownership but remain in German museums on loan.
Bronzes have also been handed back by Horniman Museum, London, and Jesus College, Cambridge, but the return of other Cambridge items was delayed after the transfer to the Oba.
Germany said last month that "to insinuate that the bronzes will disappear and never be seen again just because Nigeria, rather than Germany, is now in control is a mindset we hoped we had left behind us".
The elaborately decorated sculptures date back to the 16th century and include brass, ivory and wooden artworks depicting people, animals and royal ornaments.