In Bangladesh, flash floods have affected more than 50,000 people in the north of the country. Flooding is an annual occurrence in Bangladesh.

Officials say two days of torrential rains triggered flash floods in Maulvibazar and Haviganj districts in northeast Bangladesh, as three rivers overflowed their banks.

Tens of thousands of people in scores of villages were washed out of their homes.

Villagers joined government engineers in piling sand bags in an effort to plug the breaches.

The flooding has hit the country before the annual monsoon season has set in. That has raised worries that there will be worse to come.

The head of the Federation of Red Cross and Red Crescent Societies in Bangladesh, Mikael Sandgren, says both the government and relief agencies are preparing for such an eventuality.

"We have filled our warehouses with a lot of buffer stock, and we know the affected people will need some family kits, biscuits, rice and shelter," he said.

Floods have become an annual occurrence in much of South Asia during the monsoon season, which lasts from June to September. But Mr. Sandgren says Bangladesh is usually the worst affected in the region, because its rivers get swollen both by seasonal rains and melting snows in the Himalayan Mountains.

"Sixty-percent of the water from the Himalayas is going through this country," he said. "There is more water flowing through this country than the whole of Europe."

Last year, two-thirds of the country was swamped with floodwaters, leaving 20 million people homeless for weeks.