Yesterday’s search concentrated on three mountains – Fuar Tholl, Sgorr Ruadh and Beinn Laith Mhor. 

A Torridon team spokes-man said bad weather had initially hampered the helicopter’s involvement, but it was eventually able to join the search. 

Members of the Kintail team, of which Mr Grant is a member, joined Torridon and RAF Kinloss mountain rescue teams.

Chief Inspector Paul Eddington of Northern Constabulary, who has worked with Mr Grant on rescue missions, said: “He has the survival skills and the navigational skills to last in the hills but, obviously, as time goes by then hope does fade.

“There are more than 50 people searching for him, which shows the respect held for Pete.

“It is always difficult when these guys go looking for a missing person, but when it is one of your own there is an added poignancy.”

Police would like to hear from anyone who spoke to Mr Grant on Wednesday or Thursday and who may have information about his route.

Meanwhile, the search for a Scots walker in a South African mountain range was almost drawing to a close.

Michael Hetherington, 73, from Lossiemouth, went missing while walking in the Drakensberg Mountains five days ago.

A major search has been under way for the hiker but has since been scaled down dramatically.