GUWAHATI: At least 79 people have died and 2.2 million forced to leave their homes over the last week as torrential monsoon rains triggered floods across India's northeast, officials said Monday.

Assam state, which borders Bhutan and Bangladesh, has been worst hit with the massive Brahmaputra river breaching its banks, while extensive flooding has also hit the states of Arunachal Pradesh and Manipur.

The Assam state government said 26 of 27 districts had endured flash floods as heavy rains destroyed thousands of flimsy homes, blocked roads and swamped fields.

“So far 79 people have died in separate incidents of boat capsise or have drowned while trying to escape the gushing waters and also in landslides,” state authorities said in a statement.

The statement added 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.

“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.

Officials said more than 70 per cent of the Kaziranga National Park, famous for its tigers, one-horned rhinos and elephants, was submerged under water.

“The animals are trying to move to safer areas,” park warden Sanjib Bora told AFP.

Prime Minister Manmohan Singh and the Congress party president Sonia Gandhi visited Assam on Monday to take an aerial survey and inspect relief work.

In the adjoining states of Arunachal Pradesh and Manipur, monsoon rains caused widespread flooding but there were no reported deaths.

The monsoon, which sweeps across the sub-continent from June to September, is crucial for the region's farmers but also claims casualties from flooding every year.