The missing man told rescuers he was in thick cloud and lost

Richard March, 33, from Romsey in Hampshire, went missing on Sunday evening after calling for help on his mobile phone.

Mr Marsh is a diver by trade but also acts as a safety adviser for the film industry, and worked on the recent 007 franchise Die Another Day.

His car, which had been left in the Pen-y-Pass car park in Snowdonia, has now been towed away.

The search for Mr Marsh resumed on Tuesday morning 36 hours after he last spoke to rescue services.

Mountain rescue teams and an RAF helicopter were scrambled in an attempt to locate him.

Conditions on Snowdon can deteriorate rapidly

Teams lost telephone contact with Mr Marsh just as they were about to launch a search party on Sunday.

He had told them he intended to make his way off the mountain, but has failed to reappear.

A search was carried out during Monday but had to be abandoned as the light faded.

North Wales Police, who are coordinating the search, have said they are seriously concerned for his welfare.

Mr Marsh had told rescuers he was in thick cloud and was unsure of his location.

He had a torch but search parties were unable to spot him.

Summit

Fifteen rescue teams were deployed on Monday, with the search focusing on Snowdon's summit.

Ian Henderson, secretary of Llanberis Rescue Team, said: "They are from Llanberis, Ogwen, Aberglaslyn Rescue Teams as well as RAF Stafford.

"Members of the Search and Rescue Dog Association of Wales are also helping," said Mr Henderson.

By mid-morning on Monday, all of Snowdon was clear of cloud but still there was no trace of the walker.

Helicopter scrambled

Mr Henderson described weather conditions as being cold and fine with cloud on the top on the mountain.

Sunday's search operation saw an RAF helicopter being scrambled from Valley on Anglesey.

However, it could not get near the summit because of the worsening weather conditions.

Members of the Llanberis team were airlifted part way up the mountain.