Kenyans displaced by post-poll violence in Nairobi's slums say they are unable to go home for fear of more chaos during opposition rallies this week.

"So long as the politics and war are still there, we can't go back. We're afraid," said Collins Otiamo, 44, a businessman before a mob burned his shop, as he queued for clothes and medicine handouts in a field in the bleaching sun on Sunday.

Riots, ethnic clashes and looting erupted across opposition strongholds, including the capital's sprawling shanty-towns, after President Mwai Kibaki was narrowly re-elected at December 27 polls his opposition challenger Raila Odinga says were rigged.

An estimated 250,000 people have been uprooted and half a million may need aid.

Red Cross staff said they wanted greater efforts to resettle families but with more unrest feared after Odinga called for three days of protests starting on Wednesday, most of the displaced were too frightened to move back.

"We're doing what we can to give aid but it's hard to anticipate the time frame," Red Cross worker Allan Kilakah told Reuters as his colleagues dumped a sack of clothes on the ground with a thud from the roof rack of their vehicle.

"Clearly this is a temporary solution."

Much of the violence has targeted Kibaki's Kikuyu tribe, long resented for their prosperity and perceived stranglehold on business. Around 500 Kenyans have been killed in clashes, some of them shot dead by police opening fire on demonstrators.

Simon Ngugi used to own a flourishing flour mill making ugali - a Kenyan maize meal staple. His business was burned and now he has barely enough money for his own family's meals. His children are out of school, which restarts on Monday.

"We're afraid to go back to that school in a mixed area."

Victims of the violence also said they want cash from the government to help them rebuild their shattered businesses.