Hyderabad, Sep 2 - Andhra Pradesh Chief Minister Y.S. Rajasekhara Reddy's fate appeared uncertain Wednesday night as the air force called off its aerial search for his helicopter that went missing over 11 hours ago in a forest amid bad weather, with Home Minister P. Chidambaram saying: 'Let us hope for the best. Let us pray for the best.'

With daylight giving way to darkness in the sprawling Nallamalla forest range in and around Kurnool district, hopes of locating the Bell 430 chopper faded even as thousands of police and paramilitary personnel trekked towards an interior area over which the helicopter was spotted shortly before it lost contact with air controllers at 9.35 a.m.

A sombre Chidamabaram, overseeing the multi-faceted hunt for the helicopter, told reporters in New Delhi that the search by the Indian Air Force was called off late in the evening 'because of the weather and failing light' but said the manual search for the chopper would go on 'at least for a few hours' before resuming at first light.

Two air force helicopters from Secunderabad and three from Bangalore had searched for the American-made helicopter for several hours along with a private chopper from Andhra Pradesh.

After stating that forest and revenue department officials had conducted searches in Kurnool district, Chidambaram said: 'We are keeping our fingers crossed. The police and paramilitary forces are moving towards that point... Perhaps they would be able to do a search for a couple of hours at least, then we will have to wait first light tomorrow.

Let us hope for the best. Let us pray for the best.'

Even as rescuers combed the forest range, officials reluctantly admitted that the missing helicopter had not renewed its airworthiness certificate for two years. Experts denounced the shocking revelation.

Authorities said US satellites would be used to scan the dense Nallamalla forest. Simultaneously, a low flying aircraft of the National Remote Sensing Agency would search the missing helicopter throughout the night. The Indian Air Force said it would press Sukhoi aircraft for night operations.

President Pratibha Patil, now in Moscow, and Prime Minister Manmohan Singh expressed concern over the fate of YSR, as the chief minister is widely known. Congress president Sonia Gandhi prepared to travel to Hyderabad.

His disappearance while flying from Hyderabad to Chittoor, about 580 km away from here towards Tamil Nadu, has caused concern in the Congress where YSR is highly regarded both for his administrative acumen and political skills.