CLIMBERS have been warned mobile-phone signals in mountains cannot be relied upon for rescue calls after two Frenchmen were winched out of Glen Coe.

The two were rescued during the night after getting trapped on the Three Sisters ridge at 2000ft. Rescue crews said the pair had "wasted a lot of time" after getting lost when they tried to find a mobile phone signal.

The men, in their late twenties, managed to alert police at 10pm on Wednesday night and a Royal Navy helicopter crew from HMS Gannet searched for them.

Lieutenant Commander Andy Drodge, HMS Gannet's commanding officer, said. "We arrived in the area at 11.30pm and it was what you might describe as dark dusk.

"Fortunately, it was a relatively clear night and the two walkers did have torches which they shone when they heard the aircraft, so we located them almost instantly."

The men were taken to the base of the mountain and into the care of the rescue teams and police just after midnight on Thursday.

Lt-Com Drodge said: "Neither of the men was injured, but they were tired, anxious and starting to get quite cold. Although we did find them quickly on this occasion, they hadn't told anyone where they were going and what time to expect their return. If they had, the fact they hadn't returned would have been enough to alert the authorities much earlier.

"They had assumed they could just use their phones. Obviously, and very fortunately, they did eventually get through, but they lost themselves still further in the process and wasted a lot of time, by which time we were well into the depths of night.

"Admittedly, high summer is not the worst time to be stuck out on the hills, but even at this time of year there is a noticeable drop-off in temperature at night and, combined with altitude and the fact walkers tend to be wearing more lightweight clothing, it is not ideal."

Lt-Com added that while it can do no harm to carry your mobile phone, the remoteness of many of Scotland's mountains means you cannot rely on it if you get into trouble.

He added: "As ever, we would always recommend walkers, regardless of how experienced they are, ensure someone is aware of their planned movements for the day as well as their predicted return time."

The Three Sisters ridge runs from Sron Garbh-Am Bodach in the east to Sgurr nam Fiannaidh in the west, just above the Clachaig Inn area.