Hans Louw, a former Civil Cooperation Bureau (CCB) operative, appeared on Special Assignment on Tuesday night, detailing his alleged involvement in the assassination of former Mozambican president Samora Machel.
Machel was en route to Maputo after a meeting in Zambia when the plane he was travelling in crashed in the Lembobo mountains near Mbuzini on Sunday October 19, 1986.
Machel and 24 others died while 10 survived.
Louw said he and several other operatives from various units, including the CCB and highly trained military units, had been briefed early in October 1986 about the plot to kill Machel during the flight.
A false beacon was apparently used to trick pilots into thinking they were heading into Maputo airport, when in fact their course would lead them to crash into the mountains.
"If the plane never went down, we were the back-up team with missiles to shoot it down," he said.
He alleges there were two teams with portable missiles.
About 10 minutes before impact, the jet made a 37-degree turn in the wrong direction, heading for Swaziland.
Louw says they watched the plane go down and afterwards went to the site to make sure Machel was dead.
Another former operative, who was not named and whose face was not revealed on the programme, confirmed Louw's story.
He alleges several organisations and "top brass" were involved in the "top priority" plot.
"Some were hand-picked from Special Forces to secure the area," he said.
He corroborated the story of a false beacon, which lured the pilots off track.
Louw made his confession in 2003 while serving a 28-year murder sentence in Baviaanspoort Prison in Pretoria.
He was released on parole in August.
Returning to the site for the first time since the crash 22 years ago, Louw said it brought back bad memories.
While many have blasted his claims as untrue, Louw said: "Nobody pays me. Nobody threatens me.
"I just want people to know the truth, so I can die a dignified man because there will be no skeletons in my cupboard."
After the plane crashed, a commission of inquiry, headed by Judge Cecil Margo, concluded that the crash had been caused by pilot error.