A young soldier who embedded a pickaxe into the head of a Lance Corporal after a bust-up during army training told a court he could not believe what he had done and wished he could turn the clock back.

The axe struck L/Cpl Konrad Bisping, 26, with such force that the point pierced his skull and travelled an inch-and-a-half into his brain.

He slumped to the ground with the metal tool still embedded in his head. He survived but suffered serious brain damage.

Private Grant Kenyon, 18, denies attempted murder but admits grievous bodily harm with intent. His trial for attempted murder began at Bristol Crown Court on Tuesday.

The pair, of the First Battalion Queens Lancashire Regiment based in Catterick, North Yorkshire, clashed during a three-day training exercise at Imber on Salisbury Plain, in January.

L/Cpl Bisping was leading a platoon on an exercise in preparation for possible war with Iraq when the Private, then aged 17, hurt his ankle and began lagging behind his colleagues.

The court heard L/Cpl Bisping dropped back to remonstrate with him, during which the Private claims he was punched in the face.

Colleagues told the jury Kenyon was 'snarling' with rage after the incident.

Private Daniel Stubbs said: "He was quite angry, quite mad. He was just standing there, hacking the pickaxe into the floor quite aggressively.

"He said: 'He is picking on the wrong guy but he won't get away with this'.'"

Eye-witness Private Robert Gore said: "He was fuming. He was pacing up and down. He was bright red and snarling.

"He walked up to him (Bisping). He swung the pickaxe and struck it in his head."

Asked if he intended to kill his colleague Kenyon said: "It didn't enter my mind. I wouldn't wish that on nobody. I wasn't thinking about the consequences."

He said he lost himself when he was punched and was so angry he felt sick.

Kenyon said: "I couldn't believe I had done it. I felt shocked. I felt it had never happened I wish I could turn the clock back."

Father-of-two Bisping, from Clitheroe, Lancs, underwent brain surgery at Southampton Hospital and spent five days in a critical condition.

He was left with "devastating injuries'' including substantially reduced eyesight, the court heard. He also has a "false sixth sense" of someone always being at his shoulder.

Prosecutor Robert Davies, rejected Kenyon's claims he had not intended to kill.

He said: "The fact that Mr Bisping was not actually killed is down to luck and to the skill of the neurosurgeons at the hospital."