JOHANNESBURG, South Africa -- A Rwandan man was reportedly being sought Friday by South African police in the death of former Rwandan spymaster Patrick Karegeya whose body was discovered in a plush Johannesburg hotel on New Year's Day.

According to the opposition Rwandan National Congress coalition and the local New Age newspaper, the man was the last person to be seen with Karegeya. However, police would not confirm nor deny it, saying they were chasing up several leads.

Members of the Rwandan opposition claim Karegeya was assassinated at the behest of Rwandan President Paul Kagame.

The New Age newspaper quoted Karegeya's nephew David Batenga as saying that he and Karegeya had picked up a Rwandan man at a light-rail station on Sunday and taken him to the Michelangelo Towers Hotel in the plush Johannesburg suburb of Sandton. Karegeya was found dead in the man's hotel room on Wednesday.

Theogene Rudasingwa, Washington-based co-ordinator of the Rwandan National Congress, said in a telephone interview with the Associated Press Thursday: "We have been told the guy who was last seen with Patrick was from Rwanda, a Rwandan whom Patrick knew who used to go to Rwanda and come back. I think he pretended to be Patrick's friend."

Batenga said he had left the men after a few hours, and tried to call Karegeya on his cellphone on Tuesday evening but had received no response. The police were alerted when Karegeya's phone was still switched off the following morning, the newspaper reported.

The name of the Rwandan national reportedly being sought by police was among the names of seven people claimed in a blog run by Rwandan dissidents to belong to a hit squad sent to South Africa to eliminate Karegeya. The blog said its information came from informers.

The special police investigation force, the Hawks, says it is making progress in the investigation into what they call the murder of Karegeya. Police suspect he might have been strangled. His neck was swollen and a rope and bloodied towel were found.

"We are exploring all avenues," Hawks spokesman Captain Paul Ramaloko told The Associated Press.

Karegeya, the former head of Rwanda's external intelligence service, had been living in exile in South Africa for more than five years after having a falling out with Kagame.

Rudasingwa described Karegeya's death as an assassination that fit a pattern of attacks against prominent opponents of Kagame. The Rwandan government has vehemently denied it targets opponents for assassination.

Gunmen also twice tried to kill Kagame's former chief of army staff, Lt. Gen. Kayumba Nyamwasa, while he was living in exile in Johannesburg in 2010. Nyamwasa told The Associated Press in 2012 that Kagame has hunted him and other dissidents around the world, "using hired killer squads."

In a brief telephone interview with AP on Friday, he was reluctant to say who he believed was behind the killing of his friend and former colleague, Karegeya.

"We are not sure. It's too early to say. We're still busy piecing all the information together. I believe we should wait for the outcome of the police investigation before commenting on the matter," Nyamwasa said.

Karegeya told an AP journalist a month ago that his work organizing the opposition to Kagame was risky and could cost him his life. He also said his daughter's Rwandan passport was revoked on Kagame's orders while she was trying to leave Uganda, where she grew up in exile, and that Kagame blocked his own quest for work with the United Nations.

The Rwandan government vehemently denies targeting dissidents, and Rwandan High Commissioner Vincent Karega told local broadcaster eNCA on Thursday that talk of assassination is an "emotional reaction and opportunistic way of playing politics." He urged people to wait for the police report in South Africa, which has one of the world's highest murder rates.

Kagame has long been accused of extra-territorial killings, including ones committed when Karegeya was the feared boss of Rwanda's external security agency.