Rogue Afghan soldier kills British troops inside base

Two dead after assassin tricks his way into heavily armed compound and then opens fire

Two British servicemen have been killed by a member of the Afghan army at the headquarters of the UK mission in Helmand. The attacks yesterday were followed by the fatal shooting of a Nato soldier, believed to be an American, in the east of the country, by an Afghan policemen.

The deaths raise fresh questions about the policy on which the West's exit strategy from the war is based and will also deepen concerns about the unravelling security situation in the country where dozens of lives – both Afghan and Western – have been lost in recent weeks.

The two victims were on duty at the base in Lashkar Gar, the capital of Helmand, when they were shot by the Afghan, who was then killed by British troops. The attacker had arrived claiming to be carrying out checks for a visit of dignitaries from Kabul in order to gain access past the main gate, before opening fire.

The two who died were from the Royal Marines and the Adjutant General's Corps (Staff and Personal Support), the Ministry of Defence said last night. The fatalities take the total number of UK military deaths in Afghanistan to 407. Six soldiers were killed by a roadside bomb earlier this month, the highest number of deaths in one attack.

He arrived at the gate along with a group of Afghan troops in two vehicles, before approaching the British troops on guard saying he had been assigned as part of a security detail for a delegation of dignitaries from Kabul. There was an altercation and the Afghan started firing his M16 American-made carbine rifle.

Ghulam Farooq Parwani, deputy commander of the Afghan National Army in Helmand, said: "He used this reasoning to try and get close to the foreign troops. He got close to the foreign troops, three or four metres, and he opened fire. Then the foreign troops killed him."

Brigadier General Sherin Shah Kobadi, the Afghan Commander in Helmand, said: "Today's incident, which involved armed conflict by one of the ANA members of the Fourth Kandak of 3-215 Brigade, was a tragic event. This is still under investigation and it is unclear if the action was planned or influenced by the enemy or if he acted alone. It is a matter of the deepest regret that two ISAF [International Security Assistance Force] soldiers who came to our country to provide security are now dead."

Philip Hammond, the Defence Secretary, speaking in the House of Commons, said: "Our thoughts, as ever, are with their families, for whom this will be a deeply personal tragedy."

Military commanders warned that hastening the pull out of troops because of the rising death toll would be hugely damaging to the exit strategy.

However, the killings have raised the spectre, once again, of an enemy within. The Taliban claimed the Afghan soldier had consulted them before carrying out his attack, although there is currently no evidence to support this.

The ending of the West's mission in 2014 is predicated on security being taken over by the forces of President Hamid Karzai. This would mean British troops working in close proximity to Afghans in the intervening period. Even after the combat role is finished, a sizeable number of foreign forces, including those from the UK, are expected to serve as trainers.

This is the third occasion that British servicemen have been murdered by supposed Afghan allies. In November 2009, five of the Grenadiers Guards Battlegroup were shot down at base Blue 25 by a soldier called Asadullah. In August 2010, three members of the Royal Gurkha Rifles were killed at Patrol Base 3, in Nahr-e-Seraj. Neither of the men have been caught and on both occasions the Taliban claimed credit, although it remains unclear if they were responsible.

Following the Nad-e-Ali killings, vetting procedures including biometric testing were brought in for Afghan recruits.

These were the latest fatalities in a spate of Afghans in military uniforms turning their guns on Nato forces. Fifteen, including six American, have been killed in the last three months during an upsurge of violence which followed the burning of Korans by US officials. Altogether there have been 45 such attacks since 2007, three quarters of them in the last two years.

The enemy within: 'Green on blue' killings

The death of a Royal Marine and British soldier at the hands of an Afghan soldier came as it was revealed that another Nato serviceman had been shot by a local policeman in the east of the country. Treacherous killings by the very people Nato troops are supposed to be helping, the Afghan army and police, have become so regular they have their own term "green on blue".

Training the new forces has been repeatedly held up as the key to troop withdrawal. Yet Pentagon figures state that Afghan security forces have killed around 75 foreign service members and wounded 110 others since 2007. More than 75 per cent of the attacks have been in the past two years with 16 deaths so far this year. Those include the two latest British casualties as well as eight Americans, four French, and one Albanian. While the accidental burning of the Koran on 20 February was blamed for increased tensions, the worst loss of life this year came a month earlier when a 21-year-old Afghan soldier killed four French servicemen and wounded 16 more at a mountain-top base north of Kabul.

The largest loss for the UK was in November 2009 when a rogue Afghan policeman murdered three Grenadier Guards and two Royal Military Police at a checkpoint.

The deadliest attack yet was the killing of eight US troops and a contractor by an Afghan air force pilot in Kabul last year. Terri Judd