Opposition parties are urging President Thabo Mbeki to distance himself from Aids dissidents to avert a threatened boycott by British researchers of an international Aids conference to be held in South Africa.

The prestigious XIII International Aids Conference is scheduled to take place in Durban from July 9 to 14, with up to 15 000 Aids researchers, policy-makers and activists expected to attend.

But Mbeki's contact with American researcher Dr David Rasnick, an associate of Dr Peter Duesberg, a virologist who questioned whether HIV caused Aids, prompted reports that mainstream researchers were considering staying away from the conference.

Sandy Kalyan, Democratic Party (DP) spokeswoman on Aids, said Mbeki should apologise to South African and international scientists for entertaining Aids dissidents like Rasnick who had no scientific proof to back their theory.

Mbeki should "especially" apologise to the 20% of South Africans living with HIV/Aids, Kalyan said.

"It is ludicrous that the president of one of the most developed states in Africa, who personally rallies for an African Renaissance, will blatantly contradict his plans for growth by not addressing the Aids crisis," she said.

In the National Assembly yesterday, New National Party health spokesman Kobus Gous said he would move a motion noting the right of Mbeki and Health Minister Manto Tshabalala-Msimang "to have discussions and contact with whomever they please" but urging Mbeki to inform Parliament unambiguously of the role Aids dissidents would play in the Government's anti-Aids campaign.

This clarification was essential because of the impact media reports on the issue were having on the world Aids congress, Gous said.

Several organisations and companies in the United States have also threatened to boycott the event, citing crime and the involvement of Aids dissidents in the conference as their reasons.