Officials in Bihar, the Indian state worst affected by the inundation, said neighbouring Nepal had failed to build dams to control water surging down from the Himalayas.

But Nepal hit back immediately, claiming that Indian dams were to blame for the flooding in Nepal.

"We can't do anything about the amount of water coming from Nepal," said Purna Kumari Subedi, the member of parliament for Nepal's Banke district, which borders Bihar.

"The same thing happened last year. Because of the dam constructed at Laxmanpur on the Indian side, a lot more land on the Nepali side was extremely flooded, affecting thousands of people," said Subedi.

The dam was against Nepal's interests and should be destroyed, she said.

Nepal's foreign ministry said India could have helped to alleviate the flooding upstream in the Himalayan kingdom.

"Some of the Terai plains areas bordering India were flooded because dams on the Indian side were kept closed," said Arjun Bahadur Thapa, Nepal's foreign ministry spokesman.

"We have not been able to sit for talks with our Indian counterparts about this as we are both busy dealing with the flooding," he said.

Torrential monsoon rains triggered flooding and landslides that have killed at least 93 people and affected around 270,000 in Nepal.

But flooding described as the worst in 30 years has affected 11.5 million people in Bihar. More than 90 people have died in the last two weeks.

Over 6,000 villages were submerged with at least two million people living outdoors, said Manoj Srivastava, the state's disaster management chief.

The skies cleared Monday, but a UN official warned that rivers upstream in Nepal were still overflowing, making it unlikely the flood water would recede soon.

Bihar authorities have sought federal government intervention to tackle the issue with Nepal, claiming excessive water flow had engulfed hundreds of villages in the Indian state that in the past had been unaffected by flooding.

"We have written to the prime minister to take up the issue with the Nepalese authorities," Bihar's chief minister, Nitish Kumar, said in the state capital of Patna.

"Floods are an annual feature because all rivers originating in the upper regions of the Himalayan kingdom send massive amounts of water, especially into northern regions of the state," Kumar told reporters.

Rains have eased in Nepal but authorities are concerned about outbreaks of water borne diseases as villagers slowly begin to return to their homes.

Sonia Gandhi, the leader of India's ruling Congress party, was due to visit Bihar on Tuesday. Home Minister Shivraj Patil was also expected to visit as aid efforts intensify.