The minority Tutsi (around 14 percent of the population) and the majority Hutu have had a history of ethnic clashes since the 19th century.
The massacres were not driven solely by an ethnic hatred of one group, the majority Hutu, against the minority Tutsi, she said.
In 1959, Belgium reversed its stance and allowed the majority Hutu to assume control of the government through universal elections after independence.
In Rwanda, the political power was transferred from the minority Tutsi to the majority Hutu.
The civil war, which began in 1993, pits the Tutsi-led army against various rebels from the ethnic majority Hutus.
More than 100,000 people have been killed in conflict between minority Tutsi and majority Hutu in Burundi.
Kayibanda's successful campaign brought the majority Hutu to power for the first time in Rwanda.
The Central African nation has been ravaged by civil war between its main ethnic groups, the majority Hutu and the more powerful Tutsi.
The majority Hutus made enormous gains within the country.
The new government integrates the minority - but long dominant - Tutsi and the majority Hutu at the highest levels.