DURBAN, South Africa (AP) _ The leader of the Inkatha Freedom Party denied responsibility Friday for a club and knife attack on the Zulu king's family.

Police stepped up security at the royal compound in Kwazulu-Natal, where the queen, her daughter and other members of their family were assaulted Thursday evening. The two were hospitalized in stable condition Friday.

The ruling African National Congress was quick to blame Inkatha, its main black rival. But police said it was not immediately clear whether the attack was linked to the decades-old war between the two groups for control of the eastern KwaZulu-Natal province _ the traditional homeland of the Zulu tribe. Hundreds of people have been killed in the warfare.

Inkatha leader Mangosuthu Buthelezi once held great influence over King Goodwill Zwelithini, who broke with Buthelezi in 1994 and declared himself above politics. Tension between the royal family and Inkatha has escalated since then.

On Friday, Buthelezi said his party ``rejects with contempt the insinuation from ANC quarters that the attack can be linked to Inkatha.

``Whoever is responsible must be apprehended and charged, and until the law has run its course we demand that the ANC desist from staging a trial and conviction of the IFP by media,'' Buthelezi said.

Queen Buhle Mamathe Zulu, 45, one of the king's five wives, underwent surgery Friday morning for head injuries. Her daughter, Princess Sibusile Zulu, 24, suffered a gunshot wound to the leg and head injuries.

According to police, 10 men armed with knives, clubs and guns stormed into the yard of the royal home just after sunset in the KwaMashu black township outside Durban, attacking six people.

``A spear has been planted into the belly of the nation,'' said Dumisani Makhaye, and ANC spokesman in KwaZulu-Natal. ``Never has the proud Zulu people been so defamed and humiliated.''

Safety and Security Minister Sydney Mufamadi, an ANC member, ordered police commissioner George Fivaz to ensure a quick investigation. Fivaz said the royal family's security would be tightened.

Despite Buthelezi's denials, many people, including local news media and independent human rights investigator Mary de Haas, were linking Inkatha to the attack.

On Friday, a few neighbors gathered at Nomsa Zulu's kitchen door, which looks out on the royal home, to watch police comb the yard for clues.

``This is so frightening, because we don't know why this violence is happening,'' Mrs. Zulu said.