Matthew Psaila, 19, who lived and breathed the army, early this morning succumbed to the injuries he sustained during a military exercise on Friday, which left him underwater at Chadwick Lakes for about 10 minutes before his colleagues noticed and found him.

Private Psaila has since been in a highly critical condition at Mater Dei Hospital's intensive care unit but lost his fight for life at 1.05 a.m., a close relative told The Times.

Until yesterday, the soldier was being kept alive with the help of sophisticated medical equipment after no sign of a pulse was registered for almost 20 minutes in the ambulance which took him to hospital after the accident.

The soldier's condition took a turn for the worse on Saturday night, as his family kept vigil by his bedside, tormented by unanswered questions about the circumstances of his death.

They said on Saturday they were still in dark over what happened to their son, who was unable to swim and feared the water since childhood, but was wading through Chadwick Lakes, which can reach depths of nearly two metres, against the current on a cold winter's day.

"When he was young, Matthew would remain on the sand playing. He'd wet his feet but he never went in... For some reason, water was never his friend," his brother was quoted as saying on Saturday.

Neither the army nor the Office of the Prime Minister was in a position to say whether Private Psaila's commanding officer was aware of the fact that the young soldier could not swim or whether he was last in line during Friday morning's exercise. His family pointed out that he had told his team on more than one occasion that he could not swim.

A magisterial inquiry is underway and an internal investigation has been launched to get to the bottom of the fatal accident.

Private Psaila, whose genes seem to have been pre-programmed for the army, had joined C Company, the AFM's Quick Reaction Force, capable of providing trained personnel to intervene in high-risk operations and scenarios.

Friday's exercise consisted of teamwork, carrying logs and surmounting land and water obstacles. Private Psaila was among nine soldiers, all in combat gear, carrying a backpack of some 20kg and a rifle.