Indian rescue workers persisted with efforts on Thursday to reach hundreds of thousands of people stranded by days of flooding, but as water levels receded in some regions, officials warned of the risk of disease.

More than 350 people have been killed and around 4.5 million people forced to leave their homes across at least five states in India since the weekend after rivers overflowed and authorities were forced to release water from brimming dams.

Hundreds of villages and some towns, mainly in the south and west of the country, have been submerged, leaving hundreds of thousands of people marooned, some stranded on rooftops and in trees for days without food and water.

Petroleum, gas and power plants have also been hit and crops have been devastated. One industry lobby group said the cost could exceed 200 billion rupees (US$4.3 billion).

In India's southern state of Andhra Pradesh, where 1.5 million people are homeless, the death toll reached 118 on Thursday after the bodies of four members of a family, who were washed away in their car, were found in a stream.

Authorities said two children had also died of high fever in remote villages in the district of Khammam -- 235 km (145 miles) northeast of the state capital, Hyderabad.

Officials warned of health risks with hundreds suffering from viral fever and waterborne diseases due to lack of clean drinking water and poor sanitation.

"We have taken up massive sanitation of flood-hit villages with insecticides to kill mosquitoes and pests," said I.V. Subba Rao, the state's health secretary.

Helicopters continued to supply medicine, food, water and milk sachets to hundreds of thousands on roof tops and in relief camps in five riverfront districts.

In the western state of Gujarat, where about 25 people have died in the recent floods, efforts were underway to rescue people trapped in three buildings, which collapsed after days of being partially submerged in the textile and mining town of Surat.

The Oil and Natural Gas Corp. Ltd stopped operations for the third consecutive day and six power plants of the National Power Corp. Ltd were running below capacity due to gas shortages. Reliance Industries Ltd. has also closed down some plants at its petrochemicals complex.

Power and telecommunications had been partially restored in some parts of the town and water levels were receding in some places, authorities said, but many residents were still struggling to fight the overflowing waters.

Indian television showed pictures of people struggling to find their submerged houses and collecting utensils floating in the murky flood waters.

"I am trying to locate my house and my car. They are completely under water," said Mahesh Datta, a Surat businessman.