Members of the team that went missing on the Nanda Devi peak.

Two Indian Air Force helicopters and a rescue team scoured the Himalayan region around the Nanda Devi mountain for eight missing climbers without success on Sunday and survivors are unlikely to be found, two government officials said.

The rescue effort for the climbers from Australia, Britain, the United States and India began on Saturday when they did not return to their base camp, but it may take days to trek to the avalanche-hit area where they were last known to have been. "The first aerial recce has concluded," said Vijay Kumar Jogdanda, the top civil servant in the Uttarakhand's Pithoragarh district.

"There were only tents spotted, but no human presence. The second helicopter has left for the recce." He added, "Chances of survival are bleak," and confirmed the occurrence of an avalanche that is feared to have caught the climbers in the area around India's second-highest peak.

Officials have declined to identify them. A team of ten to 15 rescuers, comprising police, disaster response personnel and administrators has also fanned out to track down survivors, said Tripti Bhatt, an official of the Uttarakhand State Disaster Response Force (SDRF).The casualty rate in the region is almost five times higher than on Mount Everest, the world's tallest peak, she added

Equipment ranging from avalanche gear to drones and satellite phones is on hand for the rescuers, Bhatt said

But the rescuers would need at least three or four days of walking to get to the avalanche site, another official said. The climbers went missing in the Himalayas near the end of a climbing season that has been particularly deadly.

At least nine people have died on the Nepalese side of Mount Everest this year, the deadliest climbing season on the peak since 2015. Other climbers in the group who turned back earlier notified officials late on Friday when their colleagues did not return as planned, Sanjay Gunjiyal, a police official in the SDRF, told Reuters.

The team had trekked into the heart of the Nanda Devi sanctuary with the "ambition of summiting a virgin peak", British adventure company Moran Mountain, which ran the expedition, said in a Facebook post on May 12. In a Facebook post on Sunday, the company said it was working with authorities and the British Association of Mountain Guides to gather information about the expedition's fate, but would make no further comment.