Massive floods over the past week have killed at least 79 people and displaced 2.2 million as torrential monsoon rains inundate India's northeast.
Officials in Assam state bordering Bhutan and Bangladesh said 26 of 27 districts had endured flash floods as heavy rains caused the massive Brahmaputra river to breach its banks.
They reported that thousands of ramshackle homes had been destroyed, roads and had blocked, and fields had been swamped.
"The people of Assam are facing one of the worst floods in recent times that has inflicted considerable damage," Prime Minister Manmohan Singh said in the state capital Guwahati after touring the area by helicopter.
"The central and state governments are doing everything possible to provide relief to the people," he added.
Assam officials said in a statement that an estimated 2.2 million people had been displaced, with thousands of homes wrecked and more than 500,000 people being sheltered in relief camps.
"So far 79 people have died in separate incidents of boat capsize or have drowned while trying to escape the gushing waters and also in landslides," it said.
"We have opened makeshift relief camps for the displaced, while many more were forced to take shelter on raised platforms and in tarpaulin tents," Assam's health minister Himanta Biswa Sarma told AFP.
Additionally, more than 70 per cent of the Kaziranga National Park was sumberged. The park is famous for its tigers, one-horned rhinos and elephants.
"The animals are trying to move to safer areas," park warden Sanjib Bora told AFP.
In the adjoining states of Arunachal Pradesh, Manipur and Meghalaya, monsoon rains caused widespread flooding but there were no reported deaths.
Meanwhile, the death toll from landslides and flooding in Bangladesh over the last week has risen from 108 to 123, officials said, though floodwaters were declining.