Rwanda’s main opposition politician, Seif Bamporiki, was shot dead in South Africa, where he lived in exile.
Bamporiki was removed from his vehicle in a Cape Town municipality before he was killed, police said.
Preliminary investigations showed that he was killed in an assault, police said. But Bamporiki’s party, the National Congress of Rwanda (RNC), said the reason was not yet clear.
Rwanda has already been accused of targeting dissidents in South Africa.
He consistently denied the charge.
The RNC was formed in exile by opposition politicians who accuse President Paul Kagame’s government of being authoritarian and intolerant of dissent.
Mr. Bamporiki had a bedding store in Cape Town. He was delivering to Nyanga County on Sunday, when he was shot after being confronted by two men, police said.
“The deceased was removed from his vehicle and shot while the 50-year-old man who accompanied him managed to escape unscathed.
“Suspects who have not yet been arrested have fled with the deceased’s vehicle and we have reason to believe that the reason for the murder was theft,” the police added in a statement to the BBC.
RNC spokesman Etienne Mutabazi gave a different account, saying that Bamporiki was killed after a sniper fired a single shot through the car window.
It was speculated on social media that Bamporiki was killed in a political coup, but Mutabazi said he did not know if that was the case, reports the BBC’s Nomsa Maseko of South Africa’s main city, Johannesburg.
Nyanga is known for being one of the most dangerous cities in South Africa, with a high crime rate, she adds.
Former Rwandan intelligence chief and founding member of the RNC, Patrick Karegeya, was murdered in a hotel room in Johannesburg in 2014.
Another founding member of the RNC, former Army chief Gen Faustin Nyamwasa, was shot and wounded in Johannesburg in 2010.
The attacks caused a huge diplomatic dispute between South Africa and Rwanda in 2014.
South Africa expelled three Rwandan diplomats after accusing them of links to the assassination and attempted murder of Rwandan dissidents living in the country.
The Rwandan government rejected the claim.