French authorities have arrested a Rwandan doctor accused of involvement in the 1994 genocide.
Eugene Rwamucyo has been wanted by Interpol since 2006, and was dismissed from his job in a hospital in northern France last month.
Rwandan authorities, who allege Dr Rwamucyo committed war crimes during the genocide, welcomed the arrest.
Dr Rwamucyo has denied the accusations, saying he is the victim of a campaign by the Rwandan government.
He was arrested in Sannois, north of Paris, after attending the funeral of a former Rwandan official convicted for war crimes during the genocide, French officials said.
His detention is the latest in a series of moves by French authorities against genocide suspects, and comes amid improving diplomatic relations between Rwanda and France.
French President Nicolas Sarkozy visited Kigali in March and his Rwandan counterpart, Paul Kagame, is due to make a return visit to France next week.
Rwanda's Prosecutor General Martin Ngoga told Rwandan radio on Thursday that he thought France's attitude had changed.
"We are pleased," he said. "We've noticed in the past few days that France is committed to prosecuting alleged 'genocidaires' [people who committed genocide] who have taken refuge there."
Some 800,000 Tutsis and moderate Hutus were killed in the 100-day genocide in 1994.
Those most responsible for the killings are being tried by the International Criminal Tribunal for Rwanda (ICTR) based in Arusha, Tanzania.