Indian authorities sought military help in two districts of northern Uttar Pradesh state after heavy rains left hundreds of villages marooned.
As many as 33 out of 75 districts in the state are reeling from floods that have left 55 people dead.
"We have sought army's help to reach out to the affected people," T P Gupta, a senior official from the state's diaster management authority, told AFP.
Nearly 100,000 people have been moved to shelters, with authorities estimating another two million have been hit by the deluge.
In India's Bihar state the death toll reached 153.
Nearly 400,000 people have sought shelter in relief camps and an estimated 10 million have been affected by one of the state's worst floods since 2008.
Anirudh Kumar, the state's top disaster management agency official, said more than 5,000 emergency workers including 2,000 soldiers were supporting relief and rescue operations.
"Nearly 1,300 shelters have been opened to accommodate the affected people," Kumar told AFP.
Both Bihar and Uttar Pradesh border Nepal, which was hit by floods at the weekend and where the death toll is 123. At least 20 percent of the population is affected.
Further east, at least 60 people have died in floods that hit Assam state a second time in less than four months and nearly 425,000 remain in relief camps.
Authorities in West Bengal state said the flood waters were receding after a lull in the rains, with 52 deaths reported. More than a million people have been affected.
At least 100 people have died in neighboring Bangladesh with close to 6 million affected by the floods.
Every year hundreds die in landslides and floods during the annual monsoon season that hits India's southern tip in early June and sweeps across the South Asia region for four months.
A massive landslide in India's Himachal Pradesh state swept two passenger buses off a hillside, killing 46 people on Sunday.
Eight others, including two soldiers, were killed in Uttarakhand state in landslides on Monday.