Wayne Richards was training to be a Royal Marine

She said there was insufficient evidence for a "realistic prospect" of conviction against any person involved in the training exercise.

The matter will now be referred to HM Coroner for East Devon.

The CPS said it would reconsider the case if fresh evidence came to light at the inquest and was then referred back for consideration.

'Nightmare'

Earlier this year, Alan Richards, the victim's father, said he was determined to find out the truth about what had happened to his son.

"It has been one big nightmare," he said.

Mr Richards said he wanted to know how Wayne had been shot with live rounds during a mock battle.

He added that he was certain his son's death was purely accidental but said that he needed to know what the mistakes were that led to his death.

The recruit, from Cwmavon in the Swansea Valley, was in the ninth week of a 30-week course to qualify for the coveted Royal Marine green beret.

He was exercising on Woodbury Common with the 780 troop from the nearby Commando Training Centre at Lympstone when the incident happened.

At the time, the regiment described the incident as "a tragic accident".