By Peter Biles
BBC Southern Africa correspondent
South Africa is to reopen an investigation into a plane crash 20 years ago that killed the then President of Mozambique, Samora Machel.
Samora Machel died returning from a trip to Zambia
The original inquiry blamed pilot error.
But critics accused South Africa's white minority government of using a decoy beacon to cause the crash.
At the time South Africa was waging a ruthless counter-insurgency war against the exiled members of the African National Congress and their supporters.
The crash has always been one of the great mysteries of the apartheid era.
President Machel was flying home from a visit to Zambia in October 1986.
As his plane approached the capital, Maputo, it crashed into mountains on the border between Mozambique and South Africa.
South Africa was accused of luring Machel's plane into the mountains using a false beacon, although the government-appointed inquiry concluded that pilot error was the cause of the crash.
Now, 20 years later, South African Safety and Security Minister Charles Nqakula has confirmed that the investigation will be re-opened as soon as possible.
However, he did not make it clear whether new evidence had come to light.
Last Friday, the South African president, Thabo Mbeki, in his annual state of the nation address, said the 1986 plane crash still required a satisfactory explanation.
Among those who have long called for a fresh investigation is Samora Machel's widow, Graca, who is now married to Nelson Mandela.
The new inquiry will be conducted by the South African police and intelligence agencies, working with the authorities in Mozambique.