Flooding in Kenya after heavy seasonal rains has claimed 63 lives and forced tens of thousands from their homes in the past month, Vice-President William Ruto said Thursday.

"As at now, 63 people have been killed," Ruto told reporters, watching as five tonnes of food and other essential items were prepared to be flown to affected areas at a military airbase in the capital Nairobi.

"The government has directed the military to urgently evacuate people marooned by floods," he added, noting that the northeastern regions of Merti and Garbatulla were particularly badly affected.

Dozens of people die every year during Kenya's rainy season, which usually lasts from March to May.

Kenya's army said it had flown aid deliveries to the central town of Isiolo and despatched helicopters to drop food in northeastern areas where the flooding has made roads impassable.

Areas across Kenya have been affected as the heavy rains have damaged roads and property.

On Wednesday, two children were killed by a landslide caused by the rains in Kenya's Rift Valley, while helicopters were used to rescue more than 40 people marooned by floods in the eastern Garissa region.

Eight passengers were swept away as they travelled on a truck to the northern town of Marsabit earlier this month.

"The government will mobilise all the available resources to assist the affected persons," Ruto added.

Parts of Kenya suffered from extreme drought in 2011 -- like the wider Horn of Africa region, including parts of war-torn southern Somalia where famine was declared -- and farmers are welcoming the heavy rains.

However, traders are also struggling because of the impassable roads.

"All my goods will go to waste," said truck driver Sokotei Balesa, stuck in Isiolo with a load of vegetables. "I am trying to find a trader to buy them."

Parts of southern Somalia have also been affected, with the UN Office for the Coordination of Humanitarian Affairs (OCHA) warning that floods have hampered aid deliveries.

Several thousand people have been forced from their homes in areas along southern Somalia's Shabelle river, with five children reportedly killed in recent weeks, the United Nations added.

However, the heavy rains could also "bode well for the harvest", OCHA noted.