Nanda Devi: Rescued climbers search for missing mountaineers
Four British climbers who were rescued from an expedition in the Himalayas have joined an aerial search to find eight fellow mountaineers.
Two Indian air force helicopters are searching the mountains for the missing group, made up of four Britons, two Americans, an Australian and an Indian.
The mountaineers began ascending Nanda Devi on 13 May with the four other climbers, who were rescued on Sunday.
The group of four has helped to narrow down the search area, officials said.
They boarded a helicopter on Monday morning to help search efforts, the BBC's Shalu Yadav said.
Indian rescuers resumed their search on Monday after poor weather hampered progress. Rescuers have said the chances of finding the larger group are "bleak".
The four rescued climbers were named as Mark Thomas, 44, Ian Wade, 45, Kate Armstrong, 39, and Zachary Quain, 32.
They were airlifted to safety after being spotted early on Sunday at Munsiyari base camp near Nanda Devi. They had returned there to due to harsh weather.
R C Rajguru, police chief of the Pithoragarh district, said on Monday the rescued climbers have helped to give a "rough idea" of where the missing group had been trekking.
The larger group headed for the summit of another unnamed peak, government official Vijay Kumar Jogdanda said.
Both groups remained in touch until 26 May - a day before an avalanche hit the 7,816-metre mountain, according to authorities.
The missing group was led by experienced British mountain guide Martin Moran, originally from Tyneside. His Scotland-based company Moran Mountain has run numerous expeditions in the Indian Himalayas.
In a statement, his family said they were "deeply saddened" and were pressing for the search area to be widened.
Moran Mountain confirmed on Saturday that it was working with authorities and the British Association of Mountain Guides (BMG) to gather information.
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BMG said in a statement that the group had decided to attempt the unnamed summit - referred to as Peak 6447m - as part of their acclimatisation training before the planned ascent of Nanda Devi East.
Mr Moran had sent a message on 25 May indicating all was well, the weather was good and the group intended to attempt Peak 6447m in the early hours of 26 May, BMG said.
But base camp support staff alerted another BMG guide, Mark Thomas, when Mr Moran's group failed to return on the expected date. The rescue effort began on Saturday.
The rest of the group have been named locally as John McLaren, Rupert Whewell and University of York lecturer Dr Richard Payne from the UK; US nationals Anthony Sudekum and Ronald Beimel; Australian Ruth McCance and Indian guide Chetan Pandey.
Mr Jogdanda said on Sunday tents had been spotted by an aerial search, but that no human presence had been seen.
"Chances of survival are bleak," he added.
A team of 10 to 15 rescuers, comprising police, disaster response personnel and administrators, was also involved, said Tripti Bhatt, an official of the Uttarakhand State Disaster Response Force (SDRF).
Authorities warned it could take days to trek to the area where the missing climbers were last known to have been.
The British Foreign and Commonwealth Office (FCO) confirmed it was in contact with Indian authorities and would do all it could to help.
Nanda Devi is the world's 23rd highest mountain and was first scaled in 1936.
Considered one of the toughest Himalayan peaks to climb, it attracts fewer climbers than other mountains in the region.