Flash floods triggered by days of monsoon rain are affecting more than half a million people in India's northeastern state of Assam.

Officials said the situation worsened on Monday when gushing waters broke several embankments on the main Brahmaputra River, engulfing over 100 villages.

About 25,000 hectares of crops have also been submerged.

All rivers in Assam are flowing at dangerous levels threatening several new areas, they said.

The eastern district of Dhemaji was among the worst affected by a breach in the embankment, with at least 100,000 people stranded by the rising waters.

Relief efforts

The Deputy Commissioner of Dhemaji, BR Shyamal, told the BBC that relief camps were being set up to shelter thousands of marooned villagers.

He said it would take at least two months for the water levels to recede.

The authorities have pressed into service motor and other boats to ferry those stranded to safer areas.

State officials said food prices have soared and essential supplies cannot be transported to the flood affected areas.

Officials said they have requested the Food Corporation of India, the agency responsible for the procurement and distribution of foodgrains, to supply 100,000 kg of rice to the relief camps.

Annual problem

Parts of Assam and the neighbouring Arunachal Pradesh remain cut off from the rest of the country as flooding waters have destroyed transport links.

Floods in the north-east of India are an annual phenomenon.

In August 2000, floods in the region killed 100 people, and left 700,000 people in Assam alone.

Environmentalists blame soil erosion, the silting of river beds and the increasing population of flood plains.