By Omer Farooq in Hyderabad
A massive search operation has been launched for Mr Reddy
A helicopter carrying a powerful Indian politician has disappeared during a flight over a Maoist rebel stronghold in the south, officials say.
Andhra Pradesh Chief Minister YS Rajasekhara Reddy's helicopter took off from Hyderabad on Wednesday morning.
But it disappeared in bad weather as it flew over forests where Maoist rebels are known to operate, officials said.
A massive operation involving air force helicopters and fighter jets has been launched to try to locate the aircraft.
Mr Reddy is an influential politician from the Congress party and the situation is being closely monitored by federal ministers in Delhi.
Andhra Pradesh is one of several Indian states with a significant Maoist rebel presence.
"We hope that he would be safe but we could not establish any contacts as the forest is dense and heavy rains are continuing in the area," state Finance Minister K Roshaiah said.
He appealed to the people living in and around the Nallamalla forest - where the helicopter went missing - to look out for the chief minister, saying he might be stranded in a remote place.
The minister said the helicopter might have made an emergency landing because of the heavy rain in the area.
Rain has made the search operation difficult, reducing many areas to mud, he said.
The helicopter carrying Mr Reddy and four others took off from Hyderabad's Begumpet airport at 0845 IST (0315 GMT) bound for the village of Anupally in Chittoor district.
It was scheduled to land at 1045 but went missing at 0936 while flying over Kurnool district.
There are many Maoist rebels in the district and officials say they are worried about the chief minister's safety.