KHARTOUM (Reuters) - The worst floods in India's Kerala state a century ago killed 164 people and forced more than 200,000 more into aid camps, while death toll is expected to rise as water levels continue to rise as a result of heavy rains, officials said on Friday.

A disaster management official said more than 320 people had been killed by floods and landslides since the rainy season started nearly three months ago, while the prime minister of the southwestern coastal state has asked for reinforcements from the military to support relief efforts.

Rising water levels have made access to food supplies and basic needs difficult and access to safe areas difficult.

"In some areas, air transport has become the only option ... thousands are still under siege," State Minister Pinaray Vijayan said.

He said he hoped the army would step up its rescue efforts after using dozens of helicopters and hundreds of boats.