Tens of thousands of people have been forced to flee their homes amid brutal post-election violence in Kenya that had claimed at least 300 lives by Wednesday and threatens to descend into full-scale tribal conflict.

On Tuesday, at least 35 children and adults sheltering in a church near the western town of Eldoret were burnt alive by an angry mob in one of the worst incidents since the December 27 presidential elections, which were narrowly won by the incumbent Mwai Kibaki amid allegations of vote-rigging by his defeated opposition challenger, Raila Odinga.

The violence is the worst Kenya has witnessed since a failed 1982 coup.

With Kibaki belonging to Kenya's largest tribe, the Kikuyu, and Odinga to the second largest, the Luo, the violence has taken on a distinctly ethnic hue, with tit-for-tat killings and targeted arson attacks.

"What I saw was unimaginable and indescribable," said the director of the Kenyan Red Cross, Abbas Gullet, after visiting several of the worst hit areas of western Kenya on Tuesday.

"This is a national disaster," he told reporters. "From the area we visited today there are roughly about 70,000 (displaced)."

Aerial video footage taken by the humanitarian group showed hundreds of houses on fire, farms set ablaze and road blocks every 10 kilometres (six miles).

Gullet said only those from "the right ethnic group" were allowed through the barricades.

Ugandan officials also reported hundreds of Kikuyu tribespeople crossing the border from Kenya.

The victims of Tuesday's blaze were among some 400 people who had taken refuge in the church in order to escape escalating tribal clashes, survivors and police said.

They said an angry mob doused the Kenya Assemblies of God Church with petrol before lighting it.

"At least 35 people were burned to death in the church, some beyond recognition. They included women and children," Gullet told AFP.

At least another 42 were taken to hospital with severe burns, Kenyan Red Cross officials said.

In Nairobi, slum areas were overrun by rioters burning down shops belonging to members of the Kikuyu tribe and looting anything from refrigerators to basic goods.

"The big men are fighting it out over the election, but if a compromise is not reached soon, we will just be left here to die," said 63-year-old John Okwiri, clasping a mangled container cap, the only object he could salvage from his little coffee shop.

"One tribe is targeting another one in a fashion that can rightly be described as ethnic cleansing," said one senior police commander who declined to be identified.

With more than 110 people killed on Tuesday, 301 people have died in politically related-violence since polling day, according to a tally compiled by AFP.

EU monitors said on Tuesday the elections had "fallen short" of international standards and urged an independent audit of the results, increasing diplomatic pressure on Kibaki.

And the head of Kenya's electoral commission said he was pressured into quickly announcing Kibaki's election by his ruling party, despite appeals by EU vote monitors and the state-sponsored human rights commission to delay the announcement until a probe was carried out.

For his part Kibaki, 76, said in a statement "that leaders of political parties should meet immediately and publicly call for calm."

But Odinga, a flamboyant 62-year-old former political prisoner who led almost all pre-election polls, said he would only talk once the president had acknowledged electoral fraud.

While declaring that "the killing must stop," Odinga also vowed to press ahead with a mass rally in Nairobi on Thursday at which he plans to have himself inaugurated the "people's president."

He also called for foreign pressure on Kibaki.

"There is no way you are going to deal with the situation in Africa unless the international community is willing to take a firm stand against the blatant rigging of elections," Odinga was quoted as saying in London's The Daily Telegraph.

PHOTO CAPTION 

A Kenyan man flees with his children during disturbances in the streets of the Mathare slum in Nairobi.

AFP