Craig Owen, 16, from Brymbo, Wrexham, was buried when the huge dune fell in as he tunnelled on Cefn Sidan beach in Pembrey.

An inquest in Llanelli, South Wales, heard that frantic efforts were made to free him when the tunnel collapsed on August 3.

Speaking after the inquest, Professor Kenneth Pye, an independent forensic geologist, called for an urgent nationwide alert warning young adults and children of the potentially fatal dangers of digging into dunes.

He warned that urgent action should be taken before next summer to put warning signs in place at beaches around the UK.

"I think that it is an urgent matter and that something should be done as soon as possible, certainly before next summer," he said.

Llanelli coroner John Owen recorded a verdict of accidental death.

The schoolboy was on a family holiday in West Wales with his parents, Jayne and Ron Owen, neither of whom attended the inquest today, when tragedy struck.

The family were using Pembray Coastal Park as a base and it was there that Craig decided to dig a hole in a dune with friends.

Inspector Owain Richards, of Dyfed Powys Police, summarised the findings of his investigation for the inquest.

He said that Craig and four other teenagers had decided to dig a hole in a dune using folding metal shovels.

After the first hole was about 10ft deep and up to 3ft wide, a second hole was started nearby.

At some point it was decided to link the two holes, despite the fact that the second one was only about 7ft deep.

A connecting tunnel was dug with a step down between the holes and Craig continued digging inside and was almost able to stand up.

Chris Brown, 18, one of the teenagers digging in the dune, later told police of the frantic efforts made to save his friend.

Mr Richards summarised his statement: "They could now walk through the connecting tunnel," he said.

"Suddenly, the sand above the tunnel collapsed and caved in on top of Craig.

"The boys frantically used their hands to dig him out and after a few minutes they managed to get to the back of his head.

"They eventually managed to free the sand away from around his shoulders before the emergency services arrived."

Mr Richards said Michael Brown, the boy's father, was the first adult on the scene after the collapse.

He found his own son digging in the sand and ran to help, eventually giving Craig mouth-to-mouth before the arrival of rescuers.

When they arrived, the teenager's body was quickly freed and he was airlifted to Morriston Hospital in Swansea, where he was pronounced dead.