A party held in the grounds of Belgium's controversial Africa Museum has drawn criticism after attendees were pictured dressing up in colonial-style clothing, with one wearing "blackface".
The African-themed event was organised by a separate company called Thé Dansant, with a dress code described on its Facebook page as "la sape, colorful, wakanda, future african".
When photos showing partygoers dressed up were shared online, critics questioned why it was allowed to take place in the museum's grounds.
The activist group Cafe Congo, which focusses on Belgo-Congolese relations, wrote on Facebook: "Explain to me how this kind of event still exists in 2019 at the Africa Museum? Is the administration or its communications team on Xanax?"
The Brussels-based museum apologised on Instagram, saying it "was not the event organiser," adding: "We agreed to provide access to the site based on the recommendation of the municipality of Tervuren."
It said it had asked Thé Dansant change the dress code for the event but "this measure turned out to be insufficient as some of the participants still chose to wear stereotypical outfits."
"We take this incident seriously, and want to apologise for mishandling the situation in such a way that this took place," the museum wrote, adding it was working on an "ethical action plan for upcoming events".
Thé Dansant said on Facebook it regrets "that some people felt upset about some images that appeared after the event".
"Everyone interprets the dress code on his/her own way and not a single person intended to hurt or upset anyone, nor to make reference to the colonial past," it said. "As an organization, we can not entirely exclude that one or the other individual may not have followed the atmosphere of mutual tolerance and respect for African culture."
"All the visitors from African origin were very proud on Sunday," it added, highlighting that 50% of DJs were of African origin.
The Africa Museum's reopening after upgrade efforts in December 2018 sparked protests, with the President of the Democratic Republic of Congo (DRC) requesting that the country's stolen artefacts be returned.
Demonstrators were protesting what they said was the museum's archaic and imperialist position and the fact that it displays items looted from Belgium's former colonies, including what is now the DRC.