A Yorkshire university lecturer is one of eight climbers reported missing in the Himalayas.
Doctor Richard Payne, a lecturer and environmental scientist at the University of York, has been confirmed as one of the missing eight climbers, which also includes four Brits.
It is understood the group were attempting to reach the summit of India's second highest peak, Nanda Devi in Uttarakhand.
Two air force helicopters and a rescue team have been searching the area for two days after the climbers failed to return to their base camp.
Other climbers in the group who had turned back earlier from the trek alerted the authorities on Friday night.
A University of York spokesman said they remain extremely concerned for Dr Payne's safety.
The spokesman said: "We are aware of the news reports and can confirm that one of our lecturers Dr Richard Payne travelled to the Himalayas on holiday.
"We remain extremely concerned for his safety and our thoughts are with his family, friends and colleagues at this difficult time."
Dr Payne joined the university as a lecturer in environmental geography in 2015, having previously worked at 12 institutions in seven countries.
On his Twitter profile he spoke of his excitement at heading to India for a month on May 9.
He tweeted: "Later today I head off for a month in India (holiday) and China (work). I think this may be the longest period in which I haven’t checked my email since I started my PhD in 2002. Excited and a bit nervous!"
Moran Mountain, which ran the expedition, said in a Facebook post on Sunday that 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.
British Mountain Guide President, Mark Charlton, said: "The British Association of Mountain Guides' (BMG) have been made aware of an incident on or near Nanda Devi East where BMG member, IFMGA Mountain Guide, Martin Moran was leading six clients and an Indian National. The BMG is assisting where possible and is in contact with the Indian authorities.
"At the moment this is all the information we have as communication is very difficult. We will update this post when more reliable facts have been established."
A Foreign Office spokesperson said: "We are in contact with the Indian authorities following reports that a number of British nationals are missing in the Indian Himalayas.
"We will do all we can to assist any British people who need our help."