Missing Australian woman Ruth McCance is feared dead along with seven other climbers after an avalanche hit their proposed climbing route in India's Himalayas.
The experienced Sydney climber was attempting to reach India's second-highest peak, the unclimbed Nanda Devi, with a group led by experienced British mountain guide Martin Moran.
The group also included three men from the UK, two men from the US and an Indian guide.
The alarm was raised when the group failed to return to base camp last Sunday.
The group was originally made up of 12 adventurers, but was reduced to eight when four climbers due to rough conditions.
The remaining members of the group pushed on in an attempt to reach the summit and local mountaineers have reported there was an avalanche on their planned route.
The company leading the climb, Moran Mountain, posted the team had reached its second base camp at almost 5000 metres above sea level on May 22.
The complete trip was expected to take about 24 days.
A rescue team of up to 20 people – including members of the Indian-Tibetan border police and the state disaster management force – left Munsiyari on Saturday morning (local time).
But it will take them at least three days on foot to reach the avalanche site.
Poor weather has so far made it impossible to send a helicopter closer to the site, but it is hoped two rescue mountaineers may be flown in on Sunday if conditions improve.
Australia's foreign affairs department says it is providing consular assistance to the family of Ms McCance who "may be among a group of trekkers missing in the Nanda Devi area of India".
In another Facebook post on Sunday, Moran Mountain said the company was working with authorities and the British Association of Mountain Guides to gather information about the fate of their expedition.
"Out of respect for those involved and their families, we will be making no further comments at this time," the post read.
Missing Aussie is avid adventurer
The expedition's British deputy leader, Mr Thomas, remained at the second base camp with three others, but was in radio contact with the group of eight that pushed higher.
But when Mr Thomas did not hear anything after May 26 he went up to look for them. He reportedly found a single unoccupied tent.
There was evidence of a large avalanche beyond that.
Websites linked to Ms McCance reveal an avid adventurer and sailor.
The corporate coach revealed in a blog post she gave up rock climbing at age 30 because she had "run out of mental and emotional reserves".
"As much as I loved it and saw others climbing safely and well, I became overwhelmed by the risks involved, so I stopped," she wrote in May 2016 alongside a picture of a rocky cliff.
"Each time I lead a climb successfully, rather than confirming my competence it became another lucky escape from what I believed was an inevitable accident."
But, at 47 years old, Ms McCance returned to the mountains in a bid to find "wild places that nourish my spirit for as long as my body will let me".
She recounted how a 23-day trek in India became "one of the most memorable" trips in her life, and how her and a friend were "silenced" by the beauty of the mountains in France following her return to climbing.
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