Graca Machel gave her evidence in private, but a commission official said she had no doubt that her husband was killed as a result of a conspiracy involving agents from Mozambique, Malawi and South Africa's apartheid government.

A Truth and Reconciliation Commission official said later that enough evidence had been gathered for an official inquiry into the plane crash.

Mandela and Machel - close companions

The official said Mrs Machel, who is a close friend of President Mandela, gave four hours of compelling evidence, giving the names of individuals involved in the conspiracy and dates of meetings they held when they were alleged to have planned the assassination of the Mozambican president.

The Truth Commission official said Mrs Machel broke down in tears on a number of occasions .

The commission, which was established to investigate political crimes during the apartheid era, now has to decide whether to ask the South African judicial authorities to initiate proceedings against suspects.

The crash

The crash, which happened just inside South African territory, killed more than 30 of Mozambique's senior government officials alongside their president.

At the time, 12 years ago, the South African government insisted that bad weather and pilot error caused Samora Machel's plane to hit a hillside.

Survivors questioned that conclusion, alleging that the plane had been shot down.

A South African inquiry ignored evidence at the time that the plane was diverted from its correct flight path by false radio signals.

Assassination suspicions

Samora Machel was one of the fiercest opponents of apartheid.

Before his death, he allowed the then outlawed African National Congress to launch guerrilla attacks from Mozambique against the South African government.

Members of the ANC who are now in the South African cabinet believe he was assassinated to put a stop to such support.

Samora Machel's widow, Graca, is now President Nelson Mandela's close companion, and he is said to have promised her that he will find out how her husband died.