Border guards joined the army in a huge rescue effort in Surat city. Officials said the number killed since the floods hit western Gujarat and Maharashtra and southern Andhra Pradesh states nine days ago was now 240 with 179 missing.

The home ministry said it rushed units of the Border Security Force and some 1,000 personnel of the National Disaster Rescue Force to Surat in Gujarat Thursday in a bid to help its 3.5 million residents marooned in the inundated city.

The air force rushed a flotilla of helicopters to support border guards, soldiers and the coastguard in plucking people from rooftops and dropping supplies in Surat.

Conditions were beginning to ease Thursday afternoon and authorities were able to reduce the amount of water they have been releasing from the nearby Ukai dam into a river flowing through the city, an official said.

"The situation is improving as the waters have started receding due to less release of water from Ukai and the completion of high tide in the sea," said Surat administrator Vatsala Vasudevan, who estimated that 50 percent of the city remained under water.

Air force spokesman Wing Commander Tarun Singha said helicopters were working round-the-clock in Surat, which accounts for 70 percent of India's polished diamond exports and boasts some of the country's largest textile houses.

"We are losing count of sorties or tonnage of relief sent as we are throwing in every aircaft that we are getting," Singha said from the city of Bhavnagar, across the Gulf of Khambhat from coastal Surat, from where the rescue is being coordinated.

"In fact, the entire armed forces is now in action out there," Singha told AFP as Gujarat state sought 20 billion rupees (444 million dollars) in emergency federal government handouts.

Gujarat Revenue Minister Kaushik Patel said 10 million people were "seriously affected" by floods in the rain-soaked state and more than 5,200 Surat residents have been saved from imminent death, the Press Trust of India news agency reported.