Mbeki and Clinton play down differences

The talks are centred on trade and investment and the Aids epidemic

US President Bill Clinton and his South African counterpart Thabo Mbeki have pledged to co-operate in tackling Africa's problems - despite recent disagreements over the Aids epidemic.

The two presidents have been playing down their differences during the Washington talks.

Mr Clinton said the United States remained committed to fighting poverty, disease, war, famine and flood in Africa.

President Mbeki, for his part, stressed the need for urgent action to narrow the gap between the world's rich and poor countries.

[The African] challenges require of us not just standard responses, but urgent and extraordinary interventions

President Thabo Mbeki

Mr Mbeki has provoked concern in Washington over his contacts with scientists who question whether the HIV virus is the cause of Aids.

A BBC correspondent in Washington says the White House has also been disappointed over the South African president's refusal to condemn the violence in neighbouring Zimbabwe.

At a ceremony in the White House East Room, Mr Mbeki thanked his counterpart for his strong support of South Africa's transition to democracy.

"You and your administration have treated us with dignity, whatever our differences on specific matters, with sensitivity to our problems in an unwavering commitment to help us resolve these," Mr Mbeki said.

Mrs Zanele Mbeki and Mrs Hillary Clinton attended the White House ceremony

The South African leader then called for more US support and assistance in resolving Africa's various conflicts and other problems.

"These challenges require of us not just standard responses, but urgent and extraordinary interventions," he said.

Mr Clinton commended South Africa's transition from apartheid to multi-party democracy.

"You embody both the courage of the long struggle that brought democracy to South Africa and the vision now needed to define South Africa's critical role in the new century," he said.

"We must be involved in Africa," he added, pledging US help in solving Africa's problems.

Aids controversy

I never said that, it's pure invention

Mr Mbeki on his alleged doubts about Aids

After the preliminary greetings, Mr Mbeki was questioned by reporters about his alleged position that Aids is not necessarily caused by HIV - the virus widely accepted to be responsible for the disease.

"I never said that ... [it's] pure invention, pure invention," he replied.

Commenting further on the US Government's recent decision to help make anti-Aids drugs more accessible Mr Clinton sounded positive about success against the disease.

"We need to get them [anti-Aids drugs] out there at affordable prices and then develop vaccines, and I think we're going to be able to do it," Mr Clinton said.

About 34 million people in sub-Saharan Africa are thought to have been infected with HIV. A third of this number is believed to have died of Aids.