A soldier from the region shot dead his sergeant and then turned the gun on himself and took his own life following an argument at a barbecue, it emerged last night.

Corporal John Gregory, 30, of North Yorkshire, who died in what officials described as "non-hostile" circumstances near Kabul airport, in Afghanistan, had been attending a function in his honour.

Details of the incident were revealed by the family of Sergeant Robert Busuttil, 30, of Swansea, south Wales, who was said to have been shot several times by Cpl Gregory.

The family said the Ministry of Defence had informed them that during the course of the evening there had been banter between Sgt Busuttil and Cpl Gregory. At some stage, the men swung punches at each other.

''The two men then sat and talked and had a drink together - as far as everyone was aware the issue was resolved," the family said.

It is believed that later Cpl Gregory approached Sgt Busuttil, pointed a rifle at him and fired five rounds into his stomach, then three rounds into his back as he slumped forward. Then Cpl Gregory is said to have aimed the gun under his chin and fired the weapon, killing himself.

The two soldiers, both of the Royal Logistics Corps, were part of a small contingent from the British Army in the International Security Assistance Force .

Cpl Gregory, who leaves a widow, was working with the bulk fuel detachment at Kabul airport.

His father would not comment other than to say he felt "numb".

A spokesman for the commanding officer of British forces in Kabul said a police investigation was under way and a coroner's court would be convened in England.