A Watford soldier and another UK serviceman were killed in a "friendly fire" incident in Afghanistan when they were hit by an anti-tank missile attack ordered by their Danish counterparts, an inquest has heard.

Captain Tom Sawyer, from Watford who served with the Royal Artillery, and Corporal Danny Winter, of 45 Commando Royal Marines, were on a rooftop providing fire support for an operation clearing Taliban compounds north east of Gereshk in central Helmand when the incident happened.

Two other members of the patrol were injured in the explosion which happened on the evening of January 14, 2009.

Resuming the inquest at Salisbury, Wiltshire, coroner David Ridley said that the missile hit the rooftop which was about 800 metres from the Forward Operation Base (Fob) Gibraltar.

Mr Ridley said that the initial inquest opening was told that: "An unidentified type of missile hit the rooftop, as a result of the explosion both soldiers suffered severe injuries to their lower bodies."

He said that the investigations into the incident have shown that it was believed the incident was a result of "friendly fire" involving a Javelin anti-tank missile fired by British personnel.

The coroner explained that the British forces were involved in a joint operation with a Danish battle group and the order to fire the fatal missile was given by a lieutenant in the Danish Army referred to during the inquest as Soldier A.

Mr Ridley said that the Danish soldiers had declined to attend the inquest and their evidence would be given by means of witness statements.

He said: "Attempts have been made to encourage the Danes to come over to give evidence live but sadly they have declined having initially indicated they would come. The fact the family have legal representation has possibly caused the Danes to reconsider their position."

Major Robert Taylor, chief instructor in Javelin training for the anti-tank division at Warminster at the time of the incident, told the inquest: "Javelin's primary purpose is to defeat enemy armoured vehicles, its secondary purpose is soft-skin vehicles, bunkers, field fortifications and hovering helicopters."

He added that he had received feedback from soldiers returning from the field that it was also being used as an "anti-personnel weapon" from as early as 2006.

He said: "Javelin in Afghanistan offered new opportunities for it to be used in a way it hadn't been used before in pin-pointing people because it was so accurate."

He said that the troops were not given specific training for targeting personnel with the weapon and the training programme had not been changed despite the feedback from returning troops.

He said: "Had I known the detail (of the incident) at an earlier stage we would have looked at our position for further training."

He explained the Javelin system only had a single viewfinder, unlike armoured vehicles, meaning only the person firing the weapon could see the target and commanders would often ask to view the target before the shot was fired.

He said: "Only the person firing the weapon can see what he is looking at and the commander cannot look at what the firer is about to fire at. That's why when the commander takes on the shot, he wants to be absolutely confirmed for himself (by checking the viewfinder) and very often that would happen because soldiers were always very concerned about carrying out a bad engagement."

Maj Taylor added that the Danish officer who ordered the firing would not have been trained in the use of the weapon.

He said: "It's not user-friendly to those who are not trained, it would be very difficult for him to get the same sight-view, for that sort of corroboration for someone who isn't trained with someone who is trained is very difficult."

He added: "The essential point is the engagement shouldn't occur unless there is a high degree of confidence that the target is a viable enemy."

Capt Sawyer was serving with 7 (Sphinx) Commando Battery, 29 Commando Regiment Royal Artillery. He was in Helmand province deployed on operations as a fire support team commander attached to Zulu Company, 45 Commando Royal Marines.

Capt Sawyer, 26, is survived by his wife Katy, whom he married in March 2008, his parents Martyn and Susan and sister Wendy.

In a statement released after his death, his family said: "Tom was the best husband, son and brother we could ever have asked for.

"He deeply loved his family and friends and his infectious personality touched all those who knew him. Dedicated to the army and his lads; he was loyal, loud and loving. He will leave a big hole in all of our lives but will always be remembered as our hero."

Lieutenant Colonel Neil Wilson, commanding officer, 29 Commando Regiment Royal Artillery, said: "Captain Tom Sawyer died a hero, doing a job he loved and whilst taking the fight to the enemy in the only way he knew.

"He was a first-class officer with a natural flair for command and was hugely respected by all his fellow officers and by the soldiers he commanded.

"He excelled as an instructor and mentor, and the time he took to impart his knowledge and uncompromising professional standards to his battery will undoubtedly be remembered as one of his greatest gifts."

Cpl Winter, 28, from Stockport, Cheshire, was a specialist mortar fire controller and was serving in Helmand province with the mortar troop of Zulu Company, 45 Commando Royal Marines.

Lieutenant Colonel Jim Morris, Commanding Officer, 45 Commando Group, said: "Corporal Danny Winter was an exceptional Royal Marine, Mortarman and Non-Commissioned Officer with a big future ahead of him.

"Clear thinking and forthright yet loyal, warm-hearted and very approachable, he was hugely influential both within the Mortar Troop but also within Zulu Company where for the last few months he had provided them with staunch fire support and planning advice throughout the many challenges that they have faced in Afghanistan."

Lieutenant Colonel Andrew Muddiman, who was based at Fob Gibraltar, described the base as the "wild frontier" as it was surrounded by Taliban hideouts while the Danish troops were based in the more secure location of Gereshk town.

Describing the posting as a "baptism of fire", he said: "The reality was that Fob Gibraltar was one of the most embattled Fobs in Helmand at that time.

"It was about company size, 100 people at best, but during the time we are considering here those numbers had dwindled because of rest and recuperation, about a third of the strength of the Fob was absent."

He added: "The enemy had mined and booby-trapped around the Fob, just by stepping out of the door we risked stepping on something and the Taliban owned the night."

Lt Col Muddiman said that the British troops had a "good-working relationship" with their Danish counterparts although there were some concerns about "different cultures and expectations".

Describing Capt Sawyer and Cpl Winter, he said: "They were both really professional, highly competent individuals, they had both been with us through the whole thing so had a really good understanding."

The inquest, which is to last for two weeks, was adjourned until tomorrow.