A powerful cyclone intensified on Friday and was heading towards India's east coast, authorities said, forecasting a risk to life and extensive damage to property when it makes landfall in 36 hours.
Satellite images showed the storm in the Bay of Bengal to be about half the size of India.
Cyclone Phailin is expected to hit between Kalingapatnam in Andhra Pradesh state and Paradip in Odisha state on Saturday evening as a very severe cyclonic storm with a maximum sustained wind speed of 205-215 km per hour (127-134 miles per hour), the India Meteorological Department said in a bulletin at 2330 GMT.
London-based storm tracking service Tropical Storm Risk described Phailin as a Category 4 storm, one notch below the most powerful Category 5 storms.
Authorities in the affected states had been stocking shelters with rations, as well as putting disaster response teams on standby and cancelling government employees' holidays as Phailin - some 800 km from the Indian coastline - moved closer.
"The cyclone is expected to impact life and properties. The districts likely to be affected by the impending cyclone have been asked to ensure all preparedness including evacuation of people in vulnerable areas to the cyclone shelters for their safety," Odisha's Chief Minister Naveen Patnaik said in a letter to the defence minister on Thursday, asking for the armed forces to prepare to help with disaster relief.
India's largest gas field -- the Reliance Industries -operated D6 natural gas block -- lies in the Cauvery Basin off the east coast.