Patna: Food riots erupted on Wednesday in eastern India, where more than two million people have been forced from their homes and about 250,000 houses destroyed in what officials say are the worst floods in 50 years.

One person was killed in Madhepura district when angry villagers fought among themselves over limited supplies of food and medicines at overcrowded relief centres.

The Kosi river in Bihar, one of India's poorest states, smashed through mud embankments and changed course last week, unleashing huge walls of water that inundated hundreds of villages and towns.

The floods have since killed nearly 50 people in Bihar. Torrential rains have killed more than 1,000 people in South Asia since the monsoon began in June, mainly in India's northern state of Uttar Pradesh but also in Nepal and Bangladesh.

Some experts blame the floods on heavier monsoon rains caused by global warming, while others say authorities have failed to take enough preventive measures to improve infrastructure.

Officials said flood victims had looted grains at some places in Bihar. Others ran for miles under helicopters that were dropping food packets. One boy was killed and about 30 people were injured in Supaul district when food packets fell on them.

"We have enough stock of food grains but the problem is that we have limited means of transport to supply them among the villagers," Rajesh Kumar Gupta, a government official in Madhepura, told Reuters by telephone.

The UNICEF said roads had been damaged and water and electricity supplies disrupted in the affected areas. Railway tracks have been submerged and essential commodities, including food, are being transported by boat.