A British soldier was killed and three others injured when their vehicle was involved in an explosion in Afghanistan, the Ministry of Defence said yesterday.
The soldiers were on a reconnaissance mission in the desert in Garmsir in the southern province of Helmand when the b last happened on Wednesday.
One soldier was killed and another seriously injured. Two others suffered minor injuries.
An MoD spokesman said: "It is too early to say what caused the explosion. There were no Taliban in the vicinity and no follow-up contact."
The soldiers' next of kin were being informed, he added.
The Nato patrol vehicle is thought to have hit a mine to the south of the town of Garmsir, causing it to crash.
Lieutenant Colonel Andy Price, of the Royal Marines, said they were "deeply upset and deeply sorry" to announce the death of a member of the taskforce in Afghanistan and said their thoughts were with the service-man's family.
He said it was too early to tell what had caused the blast.
"A patrol had gone out on a reconnaissance to look at a specific piece of land and there was an explosion," he said.
"It could have been a mine from many years ago or it could have been a deliberate attack on us, though it's unlikely as it was in the middle of the desert."
Lt Col Price said Nato forces would continue to defend Garmsir against the Taliban, which he described as a "vital mission".
"They have attacked us on an almost daily basis and every one of them have been defeated. Unfortunately, over the last 24 hours we have had to pay a heavy price for the defence of that town."
He added that the serviceman who was seriously injured had been operated on and was "doing well". His injuries were not life-threatening, he said.
The MoD could not confirm if the serviceman who died was a Royal Marine.
His death brings the toll of fatalities of British Forces personnel in Afghanistan to 44 since the start of operations in November 2001.
The commander of the UK Taskforce in Afghanistan, Brigadier Jerry Thomas, said it was with "great sadness" he had to announce the death of the serviceman.
"My thoughts and condolences are with his family, friends and colleagues at this sad time.
"My thoughts are also with the serviceman who was seriously injured and I wish him a speedy recovery," he said.
"This tragedy is made even more poignant during this special time of year."