Rob Picheta , CNN Written by

Belgium's controversial Africa Museum has apologized for allowing a party on its grounds where guests were pictured wearing blackface and colonial-style clothing.

The party, organized by an outside events company called Thé Dansant, was African-themed and had a dress code of "la sape, colorful, wakanda, future african" on its Facebook page.

But photos showing attendees in the racist attire went viral, sparking criticism of the company and questions over why the museum allowed it to take place on its grounds.

"Dear white people, how many times do you need to be reminded that black face is never appropriate, even at an African themed party," wrote guest Patricia Slack on Facebook, alongside a picture of a white man with a darkened face.

Patricia Slack

Thé Dansant told CNN in a statement: "We're sorry for some people that were absent and took the dress code in a negative way. As an organization we neither stand behind the one person that painted his face black. But this person does not represent the whole event."

But the company insisted that "all the visitors from african (sic) origin were PROUD on Sunday." They said that "everyone interprets the dress code in his/her own way" and added: "50% of the djs were from african origin."

They later added: "There were lots of africans who all felt very positive about the event."

The museum apologized for "mishandling the situation," in a more remorseful statement posted on its Instagram page.

"When the event was announced on Facebook, we noticed that the dress code suggested by Thé Dansant would likely encourage highly clichéd and stereotypical representations of people of African origin," it said. "The museum immediately contacted Thé Dansant to point out the potential consequences of this approach, and to ask the organizers to change the dress code."

"This measure turned out to be insufficient as some of the participants still chose to wear stereotypical outfits. A number of hurtful and humiliating photos taken during the event are now circulating online."

"The Africa Museum misjudged this situation and should have played a greater role in imposing clear requirements and/or conditions in advance. We take this incident seriously, and want to apologize for mishandling the situation in such a way that this took place."

The incident is particularly awkward for a museum that has consistently batted back accusations of promoting an outdated and imperialist stance and displaying exhibits plundered from Belgium's former colonies.