UN Secretary-General Kofi Annan has said that he would spend his retirement doing grass roots work in Africa as South Africa's anti-apartheid hero Nelson Mandela hailed him as one of the best UN bosses ever.

"When I retire, we (Annan and his wife) would want to devote some time to Africa to agriculture production and also to girls' education and women's empowerment. We'll move to Africa, we'll be in Ghana and also spend some time outside," Annan told reporters after meeting Mandela in Johannesburg.

Before he steps down at the end of the year after serving two five-year terms, Annan was on the first leg of a farewell tour of Africa as UN Chief, which would also take him to Madagascar, Congo and the Democratic Republic of Congo.

Mandela said Annan was an exceptional UN Secretary-General who "introduced a new approach" of involving "everybody ? Black or White".

"The Secretary-General had done a wonderful work, because he is a man who identified with the masses of the people. Some of them (Annan's predescessors) were rather high up, they did not understand about helping Blacks," Mandela said.

South Africa's retired first Black president added that Annan was "down to earth" and a person "who does not discriminate".

Asked about the United States voting against a proposed new Human Rights Council in the UN General Assembly on Wednesday, Annan said: "We do expect the council to be established today. My understanding is the US will be able to work with the council."

The council had been criticised for including among its 53 members notorious human rights abusers such as China, Cuba, Sudan and Zimbabwe.

Before leaving for Madagascar, Annan visited the township of Soweto to lay a wreath at the Hector Peterson Memorial built in memory of students killed in a 1976 protest, which turned out to be one of the watersheds in the anti-apartheid movement.

After his talks with Madagascar's President Marc Ravalomanana, Annan will travel to Congo Republic to meet President Denis Sassou-Nguesso, who became the new chairman of the 53-nation African Union in January, taking over from Nigerian President Olusegun Obasanjo.

Annan wraps up his visit in the Democratic Republic of Congo, meeting with President Joseph Kabila and delivering an address to the Congolese people who will be holding watershed elections on June 18.