The daughter of Paul Rusesabagina, who was portrayed in a Hollywood film about the Rwandan genocide, has appealed for help to secure his release, saying she believes he was abducted from Dubai.
Rwandan officials said on Monday that Mr Rusesabagina had been arrested under an international warrant for leading "terrorist movements".
Mr Rusesabagina's daughter told the BBC the allegation was false. Her father was a human rights advocate, Anaise Kanimba added.
Mr Rusesabagina, 66, is a strong critic of Rwanda's President Paul Kagame.
The family last heard from Mr Rusesabagina after he landed in Dubai on Thursday, Ms Kanimba said.
He lived in exile, and was a US resident and a Belgian citizen, she added. "So we would love these two places to help us get him home.
"The charges they have on him are baseless," Ms Kanimba added in a BBC Newsday interview.
The Rwanda Investigation Bureau (RIB) paraded the arrested man in front of journalists in Kigali on Monday, but did not give details about where he was arrested.
It said Mr Rusesabagina had been the leader and sponsor of "extremist terror outfits", and would be tried on charges of terrorism, murder, kidnap and arson.
Mr Rusesabagina, who is from the Hutu ethnic group, became well known after the 2004 film Hotel Rwanda depicted his efforts to save hundreds of Tutsis at a hotel where he was a manager during the 1994 genocide.
About 800,000 Tutsis and moderate Hutus were killed in the genocide.
They were killed by Hutu extremists who were forced from power by Mr Kagame and his Tutsi-dominated Rwandan Patriotic Front (RPF).