An Indian helicopter carrying elite paramilitary mountaineers took off Wednesday for a "very high-risk" operation to retrieve five dead climbers and three others believed killed scaling a treacherous Himalayan peak. 

Air Force choppers spotted five bodies Monday on the slopes of Nanda Devi in India's high north while looking for the four Britons, two Americans, one Indian and one Australian believed killed by an avalanche last week. 

The remains of the three others, all part of originally a 12-member team led by experienced British climber Martin Moran, were believed to be nearby. Four other Britons split from the bigger group and were rescued on the weekend.

The operation began at 5 am when a military helicopter with four local border police mountaineers and five Air Force personnel left the nearby hill town of Munsyari.

The climbers were to be dropped by the helicopter 5,500-6,100 meters up India's second-highest mountain, said police spokesperson Vivek Kumar Pandey.

He described the mission as "a very high-risk and high-altitude operation" in a zone where avalanches are frequent.

The team led by Moran had permission to climb the eastern peak of Nanda Devi, but a Facebook post by Moran's mountaineering firm on May 22 said that they planned to attempt "an unclimbed peak" around 6,500 meters high.