A boat has capsized in a swollen-river in the flood-hit Indian state of Bihar, reports say, with many feared dead.
Villages have been deluged by floodwater
Sixty people are also missing in Bangladesh after a river burst its bank in fresh monsoon floods that are causing havoc in parts of South Asia.
Areas in north-east India, Nepal and Bangladesh are under water - scores of people have died in recent days.
Relief teams are struggling to reach over 10 million people hit by the floods.
Floods and landslides are common in South Asia during the monsoon season when annual rains combine with melting snow from the Himalayas.
At least 25 people are feared to have drowned in Bihar when the boat in which they were travelling sank in the Bagmati river.
In Bangladesh, the Jamuna river burst its banks and surged through several villages, reports say.
"The flood waters came roaring into our house and we had little time to flee," Parveen Aktar, a woman in Dhunat village, was quoted as saying by the Daily Star newspaper.
The BBC's Roland Buerk in Dhaka says that floods remain severe across the country, with 29 out of 64 districts affected.
The government says its own relief operation to distribute rice will be sufficient and is not calling for international aid.
Central areas are now coming under increasing threat as the floodwaters move south towards the Bay of Bengal.
Forecasters say low lying areas around Dhaka are beginning to be inundated though the capital itself is safe.
Threat of disease
In Bihar, 34 prisoners are said to have escaped from a jail in Darbhanga district after it was flooded.
The BBC's Anu Anand, who is in the village of Salah, says most of the local residents have fled to a nearby dam where they are huddled under plastic sheeting.
Many of them are surviving on cattle feed because there is no food to eat.
Our correspondent says the survivors now face the threat of disease as well as snake-bite.
Rescue workers are using boats and helicopters to ferry supplies to those cut off, many of whom have been on their roofs for days.
Hundreds of kilometres of roads and railways have been swept away or submerged in Bihar, hampering relief efforts.
More than four million people are affected in Bihar, the authorities say, and about 50 have died in the flooding.
In Assam state officials say the floods are the most severe in recent memory.
A breach in a dam in neighbouring Bhutan led to rivers flowing into the state bursting their banks.
The word 'monsoon' comes from the Arabic for 'season'
Describes seasonal reversals of wind direction
From April heat builds over South Asia, creating low pressure areas
Brings moisture-rich south-west winds in from the ocean
More than 7.5 million people have been affected and more than a million are homeless.
Over 50 are reported to have lost their lives in recent days in Assam.
In Nepal, meanwhile, the floods have started receding after a week of heavy rain.
At least 50 people died in the kingdom over the last week in landslides and flash floods, and thousands of others have been displaced.
While parts of South Asia have had too much rain, some areas in central and northern India are desperate for it to avoid drought.
India was hit by a massive drought in 2002 and officials say that they want to be better prepared this time.
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