While the African Union is trying to mediate an end to the political turmoil in Kenya, the UN said the absence of a political resolution makes the situation there "fragile" for civilians and aid workers alike.
There are still an estimated 255,000 people displaced by fighting among the political parties since the disputed presidential elections in December.
"Many internally displaced persons are staying without proper shelter in churches, schools and police stations," said John Holmes, the head of the UN humanitarian assistance department and emergency coordinator on Wednesday.
"A main challenge is the fact that tens of thousands of people are on the move and, hence, getting assistance to the displaced populations is difficult until the movements come to an end, and assessments establish what the exact locations and number of displaced are, and what assistance they need," Holmes said.
Holmes said the UN has been working with the Kenya Red Cross Society to bring commodities and supplies to the displaced people.
In Nairobi, Ghanaian President and current African Union (AU) Chairman John Kufuor on Wednesday began mediation efforts in Kenya between rival political factions at odds since disputed Dec 27 presidential elections.
Kufuor met Kenyan President Mwai Kibaki and was scheduled to meet opposition leader Raila Odinga, who has rejected Kibaki's re-election. Odinga has accused the incumbent of rigging the December polls and the opposition has refused to accept Kibaki's victory.