Nairobi - A UN tribunal trying the most high-profile figures accused of involvement in the 1994 Rwanda genocide was Thursday expected to pass judgement on a man accused of being one of the slaughter's top planners.

The International Criminal Tribunal for Rwanda (ICTR) - based in Arusha, Tanzania - accuses Theoneste Bagosora, 67, of helping to plan and carry out the genocide and of organizing and arming the notorious Interahamwe Hutu militia.

More than 800,000 Tutsis and moderate Hutus were slaughtered by militia in the space of only a few months following the assassination of Hutu president Juvenal Habyarimana.

Bagosora, who was the Director of Cabinet in the Defence Ministry at the time of the genocide, pleaded not guilty on 12 counts of genocide, war crimes and crimes against humanity.

The ICTR indictment accused Bagosora and three other senior military officers of taking over after the death of Habyarimana and conspiring "to exterminate the civilian Tutsi population and eliminate members of the opposition."

The charges also state that Bagosora openly announced that he was returning to Rwanda to "prepare the apocalypse" after quitting talks in Tanzania prior to the genocide.

A judgement is also expected in the case of Protais Zigiranyirazo, Habyarimana's brother-in-law.

Zigiranyirazo - also known as "Monsieur Zed" - is accused of being a member of a death squad network that killed hundreds of Tutsis and opposition figures.

The ICTR indictment accused Zigiranyirazo of setting up three roadblocks near his home and ordering the men manning them to kill all Tutsis who attempted to pass through.

The ICTR has convicted 29 people since 1997, the most recent being famous Rwandan singer Simon Bikindi.

Bikindi received 15 years for making a speech in June 1994 in which he urged Hutus to kill the Tutsi minority. (dpa)