Three British soldiers have been killed in Afghanistan after being attacked by American bombers in one of the worst "friendly-fire" incidents in recent years.

The three men from the 1st Battalion The Royal Anglian Regiment were fighting the Taleban near the Kajaki dam in Helmand province when they came under fire from two American F15 aircraft which had been called in to support the British soldiers.

An investigation has been launched into what went wrong. The American pilots would have been aware of the position of the friendly forces, but in the melee below it was clearly difficult to distinguish between friend and foe. A single bomb was dropped which killed all three soldiers and injured two others.

In a statement, the Ministry of Defence said today: "It is with profound sadness that the we must confirm that three soldiers from 1st Battalion The Royal Anglian Regiment were tragically killed in what is thought to have been a friendly fire incident in Afghanistan. Two other soldiers were injured."

A spokeswoman added: "The soldiers were taking part in a fighting patrol to disrupt Taleban activity and reassure the local population northwest of Kajaki, Helmand province, when the incident occurred at approximately 6.30pm local time."

She said: "Their patrol was attacked by Taleban insurgents and during the intense engagement that ensued, close air support was called in from two US F15 aircraft to repel the enemy. A single bomb was dropped and it is believed the explosion killed all three soldiers who were declared dead at the scene."

The injured soldiers were evacuated by helicopter to the medical facility at Camp Bastion, the main British base in Helmand, for treatment.

Lieutenant Colonel Charlie Mayo, a spokesman for British troops in Helmand Province, later confirmed that both injured soldiers were seriously hurt.

"One of them is seriously injured and the other one is very seriously injured," he told BBC Rado 4's The World at One programme.

The US Embassy in London issued a statement issuing its "condolences" to the families of those involved.

"The United States expresses its deep condolences to the families and loved ones of the soldiers who died, and we wish those who were injured a speedy recovery," it said.

"The UK soldiers were serving under the Nato-led International Security and Assistance Force (ISAF), which is helping the Afghan people to build a peaceful, prosperous, and stable country."

The Defence Secretary, Des Browne, said that morale remained very high among British forces in Afghanistan and that was too soon to apportion blame for the mistake.

"I do not want us to get into a situation where we’re blaming each other, when, as a matter of fact, US air support has saved our people’s lives on many, many occasions, particularly over the last four months in that very theatre," he told Sky News.

After previous friendly-fire incidents in Iraq and Afghanistan, in which around 12 British soldiers have died in since 1990, the military in Britain and the United States have attempted to devise new methods to prevent similar attacks.

On operations at night, all soldiers go out with infra-red systems attached to their helmets so that they stand out as friendly forces to any coalition aircraft passing overhead.

During daytime operations, the key to avoiding attacks by friendly forces is for all coalition partners to keep in constant communication, and to pass on details of all patrols to the US Air Force and to other nations patrolling the skies with ground-attack aircraft.

The death of three more soldiers from the Royal Anglians will be a huge blow for the regiment, which has lost six of its members in the last four months. The death toll of nine soldiers from one regiment in such a short period is one of the worst to be suffered by a battalion since Operation Herrick, the campaign in Afghanistan, began in 2001.

The last to die from the Royal Anglians was on August 11, when Captain David Hicks from the regiment was killed during an attack by the Taleban on his patrol base northeast of Sangin in Helmand province. The three deaths also brings the total number of British servicemen who have died in Afghanistan since 2001 to 73.

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