US envoy Jendayi Frazer said Wednesday the violence in Kenya's Rift Valley was "clear ethnic cleansing," aimed at chasing out President Mwai Kibaki's Kikuyu people. Kenya has been convulsed in violence following a disputed re-election of Kibaki in December, with more than 800 people killed. Much of the fighting has been between ethnic groups, but Frazer said she did not consider the eruption of the clashes in Kenya a genocide. The violence she saw during a visit earlier this month to the country's western region, where the fighting has pitted Kalenjin people against Kikuyu, "was clear ethnic cleansing," she told reporters on the sidelines of an African Union summit in Addis Ababa. "The aim originally was not to kill, it was to cleanse, it was to push them out of the region," she said. On Tuesday, police in helicopters fired to turn back mobs in Kenya. Gunmen killed opposition legislator Mugabe Were, and slums where a tense peace had held for days exploded with machete-wielding gangs setting fire to homes and businesses owned by Kikuyus. The international community is pressuring Kibaki and his chief rival Raila Odinga - who is a member of the Luo tribe - to share power to end the crisis over the disputed presidential election. Former UN Secretary-General Kofi Annan is negotiating, but says it will take a year just to settle on a plan for resolving the deep-rooted problems that caused anger over the election to turn to murderous hate between neighbors of decades. Kikuyus are Kenya's largest ethnic group, making up about 22 percent of the population of 38 million. Two of the three presidents since independence were Kikuyu and their domination of politics and the economy is deeply resented. At the heart of the conflict are decades-old grudges over land. The Rift Valley is the traditional home of the Kalenjin and Masai. British colonizers seized large tracts of land to cultivate fertile farms there. When much of that land was redistributed after independence in 1963, President Jomo Kenyatta flooded it with his Kikuyu people, instead of returning it to the Kalenjin and Masai. Frazer also said the US is reviewing all aid to Kenya, even though most goes to people, not the government. Most US funds in Kenya are used to fight AIDS and malaria and go to non-governmental organizations, she acknowledged, but nevertheless all funding was being reviewed. The United States previously had said it would not threaten deep aid cuts to the country despite the turmoil. Washington expected to provide Kenya with more than $540 million in assistance this year.