Rwanda's former army chief told a South African court Thursday that he was shot two years ago for defying President Paul Kagame, as he testified in the trial of six men accused of attempting to kill him.

"The reasons why I would think anyone would want me dead is that I have over the years defied the leadership, in particular President Kagame, on things that needed change," Faustin Nyamwasa told a Johannesburg court.

Three Rwandans and three Tanzanians are accused of attempting to murder Nyamwasa in Johannesburg, where he was shot in the stomach outside his home on June 19, 2010, four months after receiving political asylum in South Africa.

The former army chief said he believed that the assassination was ordered because of his claims that Kagame had ordered a former president's airplane shot down thereby sparking the genocide in 1994.

"There are facts in my mind that the president of Rwanda ordered the killing of former president of Rwanda (Juvenal) Habyarimana," Nyamwasa said.

But magistrate Stanley Mkhari refused to admit Nyamwasa's comments as evidence in the case, branding them as speculation.

Rwandan opposition parties have previously accused Kagame of ordering the shooting, a claim repeated in October by his former chief of staff Theogene Rudasingwa.

The crash of Habyarimana's plane, in which Burundian President Cyprien Ntaryamira was also killed, triggered the genocide in which an estimated 800,000 people, mainly ethnic Tutsis, were killed.

Nyamwasa himself has also been accused of ordering the shooting of the plane, a charge he has denied.

The assasination trial has strained relations between South Africa and Rwanda, which wants to Nyamwasa repatriated to serve a 24-year prison sentence after a military court last year tried him in absentia on charges of desertion, defamation and threatening state security.

He also faces terrorism charges for allegedly masterminding grenade attacks in the Rwandan capital in the run-up to 2010 presidential elections.