Mwai Kibaki, who sent troops to the affected areas yesterday to help distribute food and water, called on Kenyans and foreign donors on Saturday to fill a $100 million aid shortfall.
In a statement released by the president's office, he said: "To meet this gap, I am appealing to the Kenyan public and development partners to come forward and make a contribution to this noble cause."
Against a background of warnings that the number of needy could reach 2.5 million by February, almost double the current figure of 1.3 million, Kibaki said: "As we celebrate Christmas, let us remember those of our people who are experiencing food and water shortages."
He said 7.5 million bags of maize and 2.5 million bags of beans were being sent to affected districts but that "the population in need continues to increase due to the rapidly worsening conditions".
Money was required to buy and distribute supplies of staple foods, powdered milk, nutritional supplements and livestock fodder, he said.
Photos of famine
Kibaki's statement came as photographs of malnourished children and rotting animal carcasses appeared in newspapers for the second day, and as officials continued to offer conflicting reports about the severity of the situation that some predict might result in famine.
On Friday, John Munyes, Kenya's special programmes minister, announced that the military had been deployed to assist in relief operations in 17 districts.
The north eastern province of
Mandera is among the hardest hit
But he and three other cabinet colleagues played down claims by local politicians that the situation was getting out of control and that 12 people had already died from starvation.
Munyes, along with some aid workers, said the number and cause of the deaths reported in northeastern Kenya - an arid region bordering drought-plagued Somalia - was not clear.
An official with the Kenya Red Cross Society said: "Yes, we are getting normal reports of death, but it is hard to link the deaths to any new food shortages given that the region has experienced food shortages for some time."
On Saturday, Nairobi's two leading daily newspapers accused the government of being too slow to respond to deteriorating conditions.
The Standard said: "Famine, drought and desperation sweeps through the country but military steps in as government is blamed."
A headline in the Nation newspaper said, "At last help is coming" above a picture of a malnourished infant and a story that began: "Tales of famine at the time of the Feast [Christmas] have pricked the conscience of the nation."
The paper said it had been besieged with offers of assistance from "kind-hearted Kenyans" and noted that Britain, the former colonial power, pledged $4.7 million on Friday to a UN appeal for $25 million launched last month to deal with the crisis.