Officials in Bangladesh say flooding has killed at least six people and left thousands stranded over the past five days.
The hardest-hit areas are in the north-west, where the Ganges River burst its banks, making at least 200,000 people homeless.
Relief efforts have been stepped up.
Officials say the late monsoon floods have been caused by heavy rains and the waters running down from neighbouring India.
Local officials say the floods have killed at least 100 people since the monsoon season began in mid-June.
From the newsroom of the BBC World Service