The International Criminal Tribunal for Rwanda (ICTR) was formed in late 1994 and is trying the organisers of the genocide,
It has to date convicted 27 suspects and aquitted five.
'Bias' trial
Renzaho allegedly encouraged the raping of Tutsi women, declaring publicly that the women should be "food" for the military and, when people sought help from him, replying: "I don't care."
The 63-year-old fled into exile after Rwanda's Hutu regime fell to the then rebel movement, the Rwandan Patriotic Front (FPR) led by the current president, Paul Kagame.
Renzaho's lawyer, Francois Cantier, accused the UN tribunal of bias for not trying war crimes suspects from the FPR.
"This tribunal tries suspects only from one camp," Cartier said. "Renzaho was and still is a resolute enemy of the current government in Kigali."
He has pleaded not guilty to all charges.
Renzaho was arrested in September 2002 in the Democratic Republic of Congo (DRC) after pressure was placed by the US president, George Bush, on his Congolese counterpart, Joseph Kabila.
Washington had offered up to $5m for information leading to the arrest of about 15 Rwandans being sought by the ICTR, including Renzaho.
Ethnic minority Tutsis and moderates from the Hutu majority were slaughtered during the 100-day Rwandan genocide.