At least 45 people have died in the floods in Kenya since March, including 10 since Monday, the Kenya Red Cross said. Large parts of the capital Nairobi and other major towns are underwater, forcing thousands of residents to leave their homes.

Collins Obondo, 38, lost at least four relatives in the flooding on Wednesday in Nairobi's densely-populated Mathare neighbourhood, which lies along the Nairobi River.

"The body of my mother's neighbour was trapped right across here and it seemed as though my cousin held her ankle with her head lodged between her thighs," he told Reuters as he sifted through the remnants of his mother's collapsed house.

In neighbouring Tanzania, the death toll from the rains has reached 155, Prime Minister Kassim Majaliwa told parliament on Thursday. Hundreds of thousands have had to flee their homes in Burundi.

East Africa was hit by record floods during the last rainy season in late 2023. Scientists say climate change is causing more intense and frequent extreme weather events.

Kenyan President William Ruto said at a meeting with senior government officials that the military was deploying to help with rescue operations. His deputy, Rigathi Gachagua, said a multi-agency emergency response centre would be activated on Thursday afternoon.

Gachagua said above-normal rainfall was forecast for the next week.