Any event featuring Jacob Zuma, virginity tests and more than 25,000 bare-breasted maidens dancing for a polygamous king is unlikely to pass entirely without incident. And so it proved with this year's Zulu reed dance in South Africa.

King Goodwill Zwelithini, who has five wives, spoke out angrily against the photographing of girls undergoing virginity tests at the event, arguing that the images would be used to undermine Zulu culture.

Girls participating in the annual uMkhosi WoMhlanga are required to have their genitalia inspected to certify they are virgins. The centuries-old practice has been condemned by gender rights groups but defended by Zulus as means of combating teenage pregnancy and HIV.

Zuma was among guests at the ceremony in Nongoma, KwaZulu-Natal province, last weekend. Zwelithini, 62, condemned "rogue" virginity testers and expressed dismay at seeing pictures of the tests turn up on the internet, South Africa's Mercury newspaper reported.

"I was shocked when I received these pictures on my website," the Zulu monarch was quoted as saying. "I have no doubt these pictures are going to be used to attack this solemn culture of ours. This is a very important tradition and culture and needs to be conducted with dignity and respect without abusing and violating the dignity and privacy of the maidens."

The Mercury said there were fears that the event, in which thousands of mostly adolescent girls parade bare-breasted wearing traditional beaded skirts and necklaces, had become a target for pornography syndicates.

Before the dance, the arts and culture department in KwaZulu-Natal had insisted that only accredited photographers would be allowed to attend and anyone taking "indecent" pictures would be arrested.

It declared that women wearing trousers would be banned from the king's palace. It said the participating maidens would be taught life skills, moral regeneration and HIV/Aids prevention methods.

The ceremony sees Zulu maidens sing and ululate as they descend on the eNyokeni palace to present the king with a reed symbolising their purity. Last year one maiden died and several were injured in a stampede.

Mangosuthu Buthelezi, traditional Zulu prime minister and president of the Inkatha Freedom party, said the reintroduction of the reed dance 26 years ago was ahead of its time. "It encouraged young people towards chastity even before we were swept up in the devastating wave of the HIV/Aids pandemic," he told the gathering.

Virginity testing has been criticised because of a widespread superstition in rural areas that sex with a virgin can cure HIV/Aids – blamed for fuelling high levels of rape.