At least 120 people have been killed and eight million others affected as floods inundated over half of Bangladesh with the government struggling to deal with the situation which appeared to be worsening.

Interim government chief Fakhruddin Ahmed on Sunday asked the political parties to help in the relief work irrespective of their political differences.

In his televised address, Ahmed did not directly seek any foreign assistance for flood victims but said his government would welcome any "spontaneous" help.

"The disasters like flood creates scopes for national unity and now we have got such an opportunity," he said amid reports that 38 of the country's 64 districts have submerged, making it one of the worst floods in years.

The Disaster Management Ministry control room said the death toll from floods had reached 120 overnight and that the deluge had affected over eight million people, marooning thousands of them and forcing others to flee their homes.

"Children appeared to be the worst affected," an official of the control room said.

At least 75 embankments were damaged or washed away by the floods and people who believed they were safe have been caught unawares, a Water Board official said.

Flood Forecasting and Warning Centre has warned that the eastern part of Dhaka would be flooded as the waters were entering the city from three directions though the western part was protected by a major embankment.

Many flood shelters in central Faridpur were inundated while hundreds were forced to take refuge on rooftops.