Pauline Nyiramasuhuko, who was one of the first women to be charged with genocide, was minister for family and women's affairs in the Rwandan government when some 800,000 people, mainly ethnic Tutsis, were killed in 1994.
She was accused of direct and public incitement to commit genocide and of being responsible for rape "as part of a widespread and systematic attack against a civilian population on political, ethnic and racial grounds," the International Criminal Tribunal for Rwanda (ICTR) said.
Her son, Arsene Shalom Ntahobali, a militia leader who was jointly charged in the case, was also convicted Friday of genocide, crimes against humanity including rape and persecution and war crimes, and sentenced to life in prison.
Four local officials who were accused alongside Nyiramasuhuko and her son were all found guilty on genocide and other charges. They were handed prison terms ranging from 25 years to life.
Nyiramasuhuko, who was arrested in 1997 in Kenya, and taken to the U.N. court in Tanzania to await trial, was found guilty on seven of the counts she faced, ICTR spokesman Roland Amoussouga told CNN.
They included charges of genocide, conspiracy to commit genocide, war crimes and crimes against humanity including rape and persecution.
Two charges were dismissed, one of complicity to commit genocide and a second relating to murder and crimes against humanity. She was also cleared of two charges, one alleging direct and public incitement to commit genocide and another of inhumane acts and crimes against humanity.
The court found that Nyiramasuhuko was a member of the Interim Government that issued directives whose intention "was to encourage the population to hunt down and take action against the 'enemy' and its 'accomplices'; terms which referred to Tutsis in general."
Nyiramasuhuko also participated in many Cabinet meetings at which the massacre of Tutsis was discussed "and she took part in the decisions that triggered the onslaught of massacres in Butare prefecture."
Between April and mid-June 1994, hundreds of Tutsis were rounded up by militia members in her home district of Butare and many subjected to assaults and rape, the court said. During this time, Nyiramasuhuko ordered killings and "aided and abetted rapes" of vulnerable civilians, some of which were committed by her son, the court said.
The ICTR said it had been a complex and lengthy case, involving 189 witnesses and almost 13,000 pages of documents.
The Rwandan genocide was triggered by the April 6, 1994, shooting down of a plane carrying the nation's Hutu president.
Ethnic violence erupted and Tutsis were killed systematically by Hutus.
The United Nations estimates that some 200,000 people participated in the perpetration of the Rwandan genocide.
In all, 800,000 men, women, and children -- mostly Tutsis but also moderate Hutus -- died.