Thousands of people have marked the 20th anniversary of the plane crash in South Africa which killed Mozambican President Samora Machel.
Mr Machel was the first president of an independent Mozambique
Current President Armando Guebuza repeated a commitment to persist in the search for the truth about the crash.
Mr Machel's widow Graca, now married to South African ex-President Nelson Mandela, laid a wreath at the site.
The crash sparked theories that South Africa's then apartheid regime was to blame, but this has not been proved.
"We have converged from various parts of the world to celebrate the life and deeds of president Samora Machel, cowardly murdered by the apartheid regime on the hills of Mbuzini," Mr Guebuza was quoted as saying by news agency AFP.
South African President Thabo Mbeki also attended the memorial, describing Mr Machel as "a universal hero, a son of Mozambique and a son of Africa who dedicated his life to the freedom of us all," the AP news agency said.
South African authorities are conducting a new investigation into what happened on the night of 19 October 1986, as Mr Machel and his entourage returned from a summit in Zambia.
Mr Machel's daughter Jozina told the BBC: "We cannot have closure before we know exactly what happened to our father.
"There are many things I may doubt in life but I know there was a plot and my father was assassinated."
Mr Machel was Mozambique's first president following the country's independence from Portugal in 1974.
Thirty-five people died in the plane crash. Eight others survived.
One theory is that the plane mistook a South African airstrip for the airport of the Mozambican capital Maputo - and crashed into the hills.
But some people believe the aircraft had been diverted from its planned course by a false beacon inside South Africa.
A South African commission of inquiry found fault with the Russian pilots of the Soviet-built Tu-134 airliner.
Mr Machel is still revered as one of the leading figures in the struggle for independence in Africa.