Official death toll in Bihar state climbs to 75 but aid agencies claim thousands are missing
At least 20 people have died after an overcrowded rescue boat capsized in flood-ravaged parts of northern India.
Officials said the situation was worsening because of heavy rains and a greater discharge of water from neighboring Nepal.
The rescue boat capsized last night in Madhepura district, 95 miles north-east of Patna, the capital of impoverished Bihar state.
"The boat was overcrowded because people panicked to be rescued and clambered on board," said police superintendent O N Bhaskar.
Eight people swam to safety and 32 were rescued by army troops, he said.
An army rescue worker was among those killed.
The death toll from this year's monsoon season across India has climbed past 800. Some 1.2 million people have been marooned and about 2 million more affected in Bihar, where the Kosi river has burst its banks and submerged all roads leading to the region.
Rising waters have swept away and drowned at least 75 people in Bihar since the start of the monsoon season in June, said Prataya Amrit, secretary of the state's disaster management department.
Aid agencies claim the Indian government is playing down the scale of the disaster and not taking into account thousands of people who they say are missing after the Bihar floods.
India's prime minister, Manmohan Singh, has described the situation as a national calamity.
Authorities have rescued nearly 140,000 people and put most of them in state-run relief camps, Amrit said.
The situation was getting worse because of heavy rains in the region and the breach in the embankment in the Kosi river that is swelling on the Nepalese side.
"We can't assess the extent of the damage. It is colossal," Amrit said. "But we will only be able to tell the extent after the water recedes."
The Indian government has made available more than $200m (£110m) to combat monsoon flooding.
Almost 1,500 soldiers have boosted rescue efforts in Bihar state with air force helicopters dropping food to hundreds of thousand of people stranded by the rampaging river.
India's monsoon season, which lasts from June to September, brings rain vital for the country's farmers but often also causes massive destruction.
Despite rescue operations, officials in Bihar have warned that the real danger is still ahead.
When the swollen Kosi river burst its banks in Nepal just north of the Indian border, it changed course, flowing through a fresh channel 75 miles to the east that has no protective embankments.
The river traditionally swells to a flood peak in October.
In 2007, monsoon floods killed more than 2,200 people across south Asia and left 31 million homeless, short of food or with other problems. The UN called last year's floods the worst in living memory.