Jay Slater Missing: The Biggest Conspiracy Theories Surrounding Teenager's Disappearance

On Friday, the Guardia Civil appealed for volunteer associations, such as firefighters, and individual volunteers who were experts in rugged terrain to assist in a “busqueda masiva”, or massive search, to take place on Saturday.

The Spanish police force said the search, which will begin at 9am in the village of Masca, near to his last-known location, would be coordinated to take in a steep rocky area, including ravines, trails and paths.

The announcement came as searches for the apprentice bricklayer entered a 12th day.

Mr Slater attended the NRG music festival on the island with two friends before his disappearance and his last known location was the Rural de Teno Park in the north of the island – which was about an 11 hour walk from his accommodation.

On Friday, Mr Slater’s friend Brad Hargreaves told ITV’s This Morning he had been on a video call with him before his disappearance when he heard him go off the road.

He said: “He was on the phone walking down a road and he’d gone over a little bit – not a big drop – but a tiny little drop and he was going down, and he said ‘I’ll ring ya back, I’ll ring ya back’ because I think someone else was ringing him.”

He confirmed he could see his friend’s feet “sliding” down the hill and could hear he was walking on gravel.

But, Mr Hargreaves said he and his friend were both laughing at that point.

He added: “He didn’t seem concerned on the phone until we knew how far away he was.”

He told the programme he still had hope for Mr Slater and was “praying” for him to come home.