Most deaths were reported from the western state of Maharashtra, where 163 people have been killed in four days of incessant rains, 86 of them in the past 48 hours, officials said.

Floods had forced more than 200,000 people out of their homes in nearly 3,500 villages of Maharashtra, a relief official said.

In Maharashtra and also neighbouring Gujarat, military boats and helicopters continued to reach out to thousands who remained marooned on trees and rooftops, many without food and water, after rivers burst their banks and flooded homes.

In Gujarat, about 200 villages were cut off and the industrial town of Surat, known for its diamond-cutting and textile trades, went without power as floodwaters inundated the region, leaving around three million people homeless.

"We screamed out when we saw the soldiers, they saved our lives," said Mulji Devalia, a Surat resident, whose two-storey house was completely submerged by floodwaters.

Indian television channels said 90 percent of the town was submerged and showed pictures of people wading through waist-high water and vehicles almost totally submerged.

Officials said phone lines were down, train services to Surat suspended and there was an acute shortage of drinking water. Full-scale relief operations would begin once water levels receded, the officials added.

"It is tough to reach out to the needy, the water level is rising minute by minute," said local administrator Vatsala Vasudev.

Industrial production has been badly affected in the nearby coastal city of Hazira, with Oil and Natural Gas Corp.'s gas plant flooded and production disrupted at a petrochemicals complex run by Reliance Industries Ltd. In the southern state of Andhra Pradesh, where 112 people have perished in four days of rain, some 6,000 villages have been flooded, leaving around 1.5 million homeless and forcing thousands into trees and onto rooftops.

"We haven't eaten for three days and the children are crying because of hunger and thirst," one resident of a flood-affected village told Reuters by telephone.

Other stranded villagers said they were suffering from fever, diarrhoea and vomiting.

"The situation is terrible. The area under submergence is increasing every hour due to the backwaters," said M. V. P. C. Sastry, a senior flood official, adding that military helicopters were dropping food packets and water rations to the marooned.

Officials in the central state of Madhya Pradesh said 15 people, including three children were swept away in flash floods over the last three days. Floods have also killed at least 21 people in the neighbouring states of Chhattisgarh and Orissa.