Belgian Foreign Minister Didier Reynders has drawn criticism from minority groups for blackening his face during a charity rally in Brussels in which participants dress up in what they say are the clothes of 19th century African noblemen.

Reynders last Saturday joined Les Noirauds (the Blacks), an organization under royal patronage, which was founded in 1876 and collects money for children's charities.

All members have blackened faces and wear a white top hat and a ruff, bright green trousers and stockings. They are accompanied by a fanfare band dubbed the "Conservatoire Africain" (African conservatory).

"Deplorable" was the view on Twitter of Wouter Van Bellingen, the director of Minority Forum. He added that Belgium still lacked a national anti-racism plan, despite committing at a U.N. conference in South Africa in 2001 to devise one.

Reynders, who on his website stresses the importance of Central Africa in Belgium's foreign policy, posted pictures of himself disguised as one of the Noirauds on his blog describing how he collected funds for children's charities.

The largest country in central Africa, Democratic Republic of Congo, was a Belgian colony until 1960. Millions of Congolese are estimated to have died and the country was decimated in the late 19th and early 20th centuries when Belgian King Leopold II ran Congo as his personal fiefdom.

While Reynders received little criticism from political parties in Belgium over the rally, with even the left-leaning Greens saying the Blacks were innocuous folklore, some minority organizations and prominent Belgians of African descent said the foreign minister's participation was unacceptable.

"In other civilized countries his political career wouldn't survive this, but in Belgium he just continues," said Nigerian-born author Chika Unigwe.