SOLDIERS described yesterday how three Scots colleagues became the first British troops to be killed in a suicide bomb attack in Iraq.

Sergeant Stuart Gray, 31, Private Paul Lowe, 19, and Private Scott McArdle, 22, all from the Black Watch and from Fife, died in a blast at a checkpoint during their regiment's deployment to Camp Dogwood, south west of Baghdad. They were blown 30 yards into a ditch by flames that shot 100ft in the air, an inquest was told. An expert said they had been killed by the "blast wave".

The soldiers were supporting US troops who were attacking the insurgent stronghold of Falluja. A local interpreter assisting the troops was also killed by the explosion.

The deaths happened on November 4 last year on a road about 16 miles from their base, east of the Euphrates river, the inquest in Oxford was told.

The soldiers had been due to meet an American unit, but when they were delayed it was decided to set up a vehicle checkpoint to secure the area.

The dead men had been manning the checkpoint on the ground between two Warrior armoured personnel carriers (APCs).

The controversial deployment of BlackWatch troops to Camp Dogwood, close to Baghdad and away from British-controlled southern Iraq, was ordered to free up US troops for a major assault on Falluja.

Nicholas Gardiner, the Oxfordshire coroner, recorded verdicts of unlawful killing on the three soldiers.

Recalling events at the hearing, Private AndrewMcMenemy said he witnessed "flames 100ft in the air"when the car bomber struck.

He said he saw a saloon car being driven by a local man approaching the checkpoint. Moments after it was flagged down, the vehicle exploded into what he described was a fireball which lifted him into the air.

Private McMenemy said that as he was treated for injuries to his arms and legs, the checkpoint came under mortar attack.

Another survivor, Private Damien Gonsales, said: "I remember seeing a red Opal Omega carwhich appeared to be travelling at a normal speed and it slowed down as it approached. All of a sudden it exploded in front of me."

He said he was between 10 and 20 yards away from the blast, which caused him extensive injuries.

The soldiers' commanding officer, Lieutenant Alexander Ramsey, said he had just stepped into the turret of an APC when he heard and felt what was "clearly a big explosion". He said: "Initially the only casualty I remember seeing was the locally employed civilian (interpreter) about 10 metres in front."

The other three victims had been thrown into a ditch 30 yards away. Mr Ramsey said a crater left by the blast was six to eight feet wide and two feet deep.

Staff Sergeant Michael Batten, from the Army's Special Investigation Branch, said his team could not get near the blast site because it was too dangerous. He said while the three BlackWatch soldiers had been the first UK soldiers to be killed in this way in Iraq, from then on suicide bombers were constantly circling the troops.

Nicholas Hunt, a pathologist, said the soldiers were killed by the force of the blast.

He said the trio's body armour, protecting the heart area, would have stopped shrapnel but would have been of little use against the blast wave as they were so close to it.

Craig Lowe, 18, also a Black Watch soldier, had said his brother Paul had not believed in the "money and oil"war that claimed his life, and called for troops to be withdrawn.

McArdle's fiancee, Sarah McLaren, gave birth to a baby daughter three months after his death. His mother, Sandra McArdle, earlier this year condemned the BBC's decision to show a film of the attack on her son in a documentary, The New al Qaeda.

Family members attending yesterday's inquest were too distressed to comment afterwards.

As the Oxford inquest was sitting, it emerged that Iraqi border guards had discovered another cache of explosives aimed at killing British soldiers in the area.

The weapons were found around 12 miles from the Iranian frontier, close to the border between Basra and Maysan provinces in British-controlled southern Iraq.