.CAPE TOWN, South Africa (AP) – A video made by white students showing black university employees duped into eating food that had been urinated on has prompted angry protests and criticism that racism remains entrenched in South Africa.

The video, which was made last year and surfaced this week, depicted a mock initiation ceremony into a campus residence, with black cleaners portraying students. They were shown on their knees eating food, but were not told about the urine.

Authorities at the University of the Free State said Wednesday they were investigating. Two of the students involved left the university last year and the other two have now been barred from campus.

The university suspended all classes to allow emotions to calm after a tense morning of protests during which police used a stun grenade to disperse stone-throwing students. Five students were arrested and later released.

The university in the city of Bloemfontein is regarded as a bastion for Afrikaaners, who are often linked with white apartheid rule.

University authorities have been trying to implement more racial integration at campus dormitories – and it was defiance of this policy that apparently prompted the video.

Students from the Reitz men’s residence filmed the video last year. The middle-aged black cleaners seem to know and trust the students, laughing as they try to eat the food. Unknown to the cleaners, one of the students urinated on the food beforehand, according to the video footage.

The four white students, speaking Afrikaans, make sarcastic reference to the university’s policy of integrating non-whites.

The rector, Professor Frederick Fourie, condemned the video and promised to deal “swiftly and firmly” with the matter, a university spokesman said.

Fourie said he met the workers shown on the video and apologized to them.

The South African Human Rights Commission said it was investigating complaints that the university actually condoned and allowed violations of human rights and tolerated racism.

Education Minister Naledi Pandor also sent a top official to investigate the matter.

The premier of the Free State province, Beatrice Marshoff, told protest marchers that racist acts at the institution, which had so far gone unreported and unchallenged, would no longer be tolerated.

The leader of the white-dominated Democratic Alliance party, Helen Zille, demanded that the human rights commission take action. The country’s last white president, FW De Klerk, also condemned the video.

Multiracial elections in 1994 ended decades of white rule. But racial undercurrents remain strong even today and permeate almost every aspect of South African society.