MBUZINI, South Africa - Mozambique's President Armando Guebuza on Thursday blamed South Africa's former apartheid authorities for the death of independence leader Samora Machel, who was killed in a mysterious plane crash 20 years ago.

South African President Thabo Mbeki speaks at a service to commemorate the 20th anniversary of the plane crash which killed Mozambique's founding leader Samora Machel October 19, 2006. Hundreds of South Africans and Mozambicans gathered for the memorial service on an isolated hillside outside Mbuzini in South Africa where Machel's plane slammed to the ground on October 19, 1986, killing him and 34 other people aboard.[Reuters]

At a ceremony marking the anniversary of the crash that also killed 34 other people, Guebuza said Mozambique would not rest until the truth is revealed.

"The results are not only in the interest of Mozambique," he said. "Samora Machel was a citizen of the entire world."

The thousands gathered for the ceremony included South African President Thabo Mbeki and Machel's widow, Graca.

Machel was flying back to Mozambique from a conference in Zambia when his Russian plane crashed into a South African hillside near the Mozambican border.

The South African government at the time blamed error by the Russian pilots, seeking to quell speculation about sabotage by the apartheid authorities. Speculation has continued ever since. No conclusive evidence was uncovered by South Africa's Truth and Reconciliation Commission, which sought to uncover apartheid crimes.

"Everyone asks themselves why the apartheid regime had dared to take out the life of a man ... whose views had already been transformed into his people's heritage," Guebuza said in remarks broadcast on South African radio.

The white government in South Africa had pressured Mozambique into ending support for exiled African National Congress leaders in return for a commitment that it would stop supplies to rebels fighting the Mozambican government.

Machel, who fought against Portuguese colonial rule and steered the country to independence in 1975, is still widely revered in Mozambique as a hero.

Mbeki paid tribute to Machel as "a universal hero, a son of Mozambique and a son of Africa who dedicated his life to the freedom of us all."

He spoke of the close ties between South Africa and Mozambique - further cemented by the marriage of Graca Machel to anti-apartheid icon Nelson Mandela.