Sadi Bugingo was charged with supervising killings of 2,000 people and coordinating attacks by Interahamwe militia that targeted Tutsis and moderate Hutus in Rwanda.

Prosecutor Petter Mandt said the prosecution "would not try to prove that the defendant had personally killed anyone, but evidence would be presented stating that he took part in meetings, and had ordered others to commit the killings and supervised killings," the Norwegian broadcaster NRK reported.

The prosecution was aware that Bugingo had helped some people survive, Mandt added in his opening remarks.

The 47-year-old also was charged with transporting refugees and armed killers to locations in Kibungo, in eastern Rwanda, where killings took place, including at a local government building in the community of Birenga.

An estimated 1,000 people who had sought refuge there were killed by militia, police, military and civilians armed with guns, machetes, clubs and hand grenades, according to the prosecution.

Bugingo has lived in Bergen, Norway, since 2001. He was arrested last year and if convicted could be sentenced to a maximum 21-year prison term.

Norwegian authorities have investigated Bugingo since 2008 after being contacted by Rwanda.

The trial is expected to run for three months. The proceedings were held in the same court room at the Olso district court where convicted Norwegian mass murderer Anders Behring Breivik recently was on trial.

About 100 witnesses were due to testify, of which 20 would take the stand in Oslo, and the remainder via video link.

Meanwhile, prosecutors in neighboring Sweden were preparing to charge another Rwandan man, who holds Swedish citizenship, over similar crimes, Swedish Radio news reported.

The charges likely were to be presented in November. Swedish prosecutor Magnus Elving said part of the trial could be held in Rwanda, the report said.

The 1994 Rwandan genocide is estimated to have claimed the lives of 800,000 Tutsis and moderate Hutus.