About 10 million people out of the 27 million population of Assam state have been affected by flooding after rains in the past few days. More than 2,000 villages have been completely submerged.
The second spell of flooding in less than a month has also spread across parts of Bangladesh, forcing around a million from their homes and leaving thousands stranded. About 850 people have died in floods there since late July.
About 3 million people in Assam are living in temporary shelters, government buildings and schools, officials said.
Around 1 million acres of farmland have been flooded.