Hyderabad, Sep 2 - Andhra Pradesh Chief Minister Y.S. Rajasekhara Reddy remained untraced Wedneday evening, nearly seven hours after his helicopter went missing amid bad weather in a densely forested Maoist stronghold, triggering a desperate search by the military and police.

The government said at least five Indian Air Force and one private helicopter had joined the hunt for the missing chopper that carried YSR, as the 60-year-old chief minister is known, and his special secretary besides two pilots from Hyderabad to Chittoor, 588 km away and closer to Tamil Nadu.

Flanked by Finance Minister K. Rosiah, Chief Secretary Ramakanth Reddy urged people in the Nallamalla forest area that covers Kurnool and adjoining districts to alert the police if they learnt anything about the helicopter.

YSR's fate caused tremors in New Delhi, where the office of Prime Minister Manmohan Singh and Congress president Sonia Gandhi were in touch with the state government, Reddy told reporters here.

The state government had also alerted both the home and defence ministries in New Delhi.

The chief secretary said two air force helicopters from Secunderabad and three from Bangalore were looking for the chief minister's helicopter along with a private chopper from Andhra Pradesh.

Andhra Pradesh has also urged New Delhi to send an unmanned aircraft to the area.

The state government had lost touch with the chief minister at around 9.45 a.m.

'So far we have not been able to get any confirmation (about the chief minister). It is possible that because of the strong winds and heavy rains, it may have landed in some unfamiliar area,' Reddy said. 'If you land in an unfamiliar forested area, getting out will be very difficult.