Some suburbs of the Bangladeshi capital, Dhaka, are under water as flooding worsens in central areas of the country, officials say.
People in the suburbs of Dhaka are heading for higher ground
More than 200 people have lost their lives, and 20 million are affected, in some of the worst flooding in years.
Residents in low-lying areas of Dhaka have fled their homes for the safety of higher ground in the city centre.
Millions of people are also suffering in India's north-east as a result of the monsoon floods.
Flood forecasters in Bangladesh expect the situation around Dhaka to deteriorate further as rivers keep on rising.
In some outskirts of the capital, boats have replaced cars and rickshaws as the only means of transport.
In the north-east, the situation remains largely unchanged, officials say.
About two-thirds of Bangladesh is affected by the flooding, which officials say is the worst in 15 years.
Crops on more than two million acres of land, thousands of kilometres of road and nearly two million homes have been destroyed, officials say.
The government decided on Thursday against issuing an international appeal, saying it had sufficient food supplies for the moment.
In the north-eastern Indian state of Assam, all but one of 27 districts are battling the floods, and over 100 people have died, officials say.
Millions are homeless and crops, homes and roads have all suffered huge damage.
The BBC's Subir Bhaumik, who is in the state, says the air force has been airlifting supplies of fresh drinking water.
"We will sleep in the open, we will do everything on the road but if we don't have drinking water, we will perish," one woman told him.
Bihar state has also been badly hit - the authorities say 225 people have died in heavy rains this month.
Elsewhere in India, however, many face a drought threat.
The government says vast swathes of northern, western and central India have experienced insufficient rainfall.