Afghan policeman kills five British troops..

Five British soldiers have been killed and several others injured in a gun attack by a "rogue" Afghan policeman in Helmand province, the Ministry of Defence said today.

The soldiers – three from the Grenadier Guards and two from the RoyalMilitary police – were killed by gunshot wounds suffered in the attack, which happened in the Nad-e'Ali district yesterday.

British and Afghan officials said the men were killed at a police checkpoint when the policeman picked up his weapon and began firing.

They said the attacker's motives were unclear, adding that the incident was being investigated by Afghan authorities and the Royal Military police.

"The soldiers concerned were mentoring Afghan police," Lieutenant Colonel David Wakefield, an army spokesman, told Sky News.

"They were working inside and living inside an Afghan national police checkpoint.

"It would appear, and it is our initial understanding, that an individual Afghan policeman, possibly acting with another, started firing within the checkpoint before fleeing the scene."

Wakefield stressed that the attack had not come as a result of any breakdown or fight between British and Afghan forces.

The casualties were evacuated to hospital at Camp Bastion, with several flown there in Chinook helicopters and a US Black Hawk.

Two injured Afghan policemen were taken to hospital at Bost, in Lashkar Gah.

Peter Galbraith, a former deputy head of the UN mission in Afghanistan– who left his post over disagreements about the presidential elections – said "rushed" attempts to train extra Afghan officers for the now cancelled presidential election runoff meant such incidents could be expected.

"It is a terrible tragedy … but it is, I won't quite say inevitable, but it is not surprising," he told BBC Radio 4's Today programme.

He said police usually received an eight-week training course, but it had been shortened to five weeks in order to have more police available for the elections, particularly in Kandahar and Helmand provinces, he added.

"The process of police training and recruiting has been very rushed," he added. "There isn't a lot of vetting of police before they are hired.

"It is not totally surprising that people were recruited who may have had Taliban sympathies or were infiltrated into the police by the Taliban, although I don't know yet whether, in this particular episode, that is exactly what happened."

The deaths make 2009 the bloodiest year for the British armed forces since the Falklands war, bringing the total so far to 93.

Until now, the worst period since the Falklands conflict had been 2007, when 89 members of the armed forces died on active service.

The death toll in Afghanistan since the conflict began in 2001 now stands at 229, and the increasing number of casualties has led to growing questioning of the eight-year war.

The prime minister, Gordon BrownGordon Brown, paid tribute to the soldiers, describing their deaths as a "terrible loss".

"My thoughts, condolences and sympathies go to their families, loved ones and colleagues. I know that the whole country, too, will mourn their loss," he said.

"They fought to make Afghanistan more secure, but above all to make Britain safer from the terrorism and extremism which continues to threaten us from the border areas of Afghanistan and Pakistan.

"I pay tribute to their courage, skill and determination. They will never be forgotten."

Brown said it was his "highest priority" to ensure troops had the best possible support and equipment and "the right strategy, backed by our international partners, and by a new Afghan government ready to play its part in confronting the challenges Afghanistan faces".

The defence secretary, Bob Ainsworth, offered his condolences to the families of the soldiers and emphasised the need for the country to show "resolve" in supporting the Afghan conflict.

"It continues to be a difficult year in Afghanistan for our brave people who are operating within the most challenging area of the country," he said.

"We owe it to them to show the resolve that they exhibit every day in building security and stability in Afghanistan and protecting the UK from the threat of terrorism."

Earlier this week, the MoD announced that a senior army explosives expert had been killed while defusing a bomb in southern Afghanistan.

Staff Sergeant Olaf Sean George Schmid died as he tried to make safe an improvised explosive device in the Sangin region of Helmand on Saturday.

The 30-year-old had been about to end his tour of duty after five months in Afghanistan.

Abdullah AbdullahAbdullah Abdullah, President Hamid KarzaiHamid Karzai's closest challenger in the disputed Afghan presidential election, also offered his condolences to the relatives of the dead soldiers and stressed the need for international troops.

"Eight years down the road, we still need more troops in the absence of a credible and legitimate partner," Abdullah, a former foreign minister, said. "More soldiers and more resources are the only thing we can resort to."

The latest fatalities came as a major rift opened in the British government's support for the Afghan war, with the former Foreign Office minister Kim Howells calling for the phased withdrawal of UK troops from Helmand.

Howells, who is now Brown's intelligence and security watchdog, said the billions of pounds saved should be redirected to defending the UK from terrorist attacks by al-Qaida.

Writing in the Guardian, Howells – who had ministerial responsibility for Afghanistan until 2008 – said: "It would be better to bring home the great majority of our fighting men and women and concentrate, instead, on using the money saved to secure our own borders [and] gather intelligence on terrorist activities inside Britain."