The confirmed death toll passed 700 and more than a million were driven from their homes as large swathes of South Asia reeled under monsoon floods Sunday, officials said.

More than 16 million people have been affected by floods across India, Bangladesh and Nepal, aid workers and officials said, with heavy rains and damaged roads hampering relief efforts amid severe food shortages and a growing risk of waterborne diseases.

At least 100 deaths were reported overnight across India and Bangladesh following the latest in a series of deluges since August 10, as the annual monsoon hit the north and east of the region.

Anirudh Kumar, a top disaster management official in India's eastern state of Bihar, said 53 bodies were recovered as water levels started to recede in some areas.

"The total death toll stands at 205," Kumar said.

Nearly 400,000 people were staying in state-run shelters, with an estimated 10 million affected by the deluge, the worst since 2008 when nearly 300 people were killed.

Some 10,000 emergency workers and soldiers were supporting local officials in relief and rescue operations. In neighbouring Uttar Pradesh state 69 deaths were reported as two million residents remain affected by the floods.

Nearly half of the 75 districts in the state have been hit by the floods and authorities are seeking military help to evacuate people in at least two districts.

Both the states border Nepal, which was also hit by landslides and floods that killed 135 people. Another 30 are reported to be missing.

At least 20 percent of the 28 million people in the landlocked Himalayan state are affected by what the United Nations has called the worst floods to hit the country for 15 years.

In India's eastern state of West Bengal and in the remote northeastern state of Assam, 122 people have died with nearly three million affected by floods.

More than 450,000 people were living in relief camps in Assam after the second wave of floods to hit the state in less than four months.

The deluge has badly damaged railways and roads.

'Situation improving'

Three more bodies were retrieved in a northern village in West Bengal state, where 55 people have now died. More than a million have been affected, although officials say the situation is fast improving.

In Bangladesh at least 115 people have died and some 5.7 million people have been affected by the floods, Shamim Naznin, head of the control room at the department of disaster management, said.

She said 31 of the country’s 64 districts have been hit by the floods, forcing nearly 300,000 people to flee their homes and take refuge in makeshift shelters.

The state flood forecasting and warning centre said some 30 percent of the country has been inundated, the worst flooding for a decade.  

But the situation in the country’s north and west was improving quickly because the level of major rivers was falling fast, officials said.  

Every year hundreds die in landslides and floods during the monsoon season that hits India's southern tip in early June and sweeps across South Asia for four months.

A massive landslide in India's Himachal Pradesh state swept two passenger buses off a hillside, killing 46 people on August 13.

Eight others, including two soldiers, were killed in Uttarakhand state in landslides on Monday.

Nearly 350 people died in the first wave of floods that began in mid-July in India's western states of Gujarat and Rajasthan and several remote northeastern states.