KABUL: Two soldiers in the Nato-led coalition fighting insurgents in Afghanistan were shot dead Tuesday by a man in an Afghan police uniform, the alliance's International Security Assistance Force (Isaf) said.

The incident was the latest in a series of insider attacks that had seriously undermined trust between Nato forces and their Afghan allies in the fight against hardline Islamist Taliban insurgents.

“An individual wearing Afghan National Police uniform turned his weapon against Isaf forces in southern Afghanistan, killing two soldiers,” a spokesman told AFP.

The Taliban claimed that the shooter was one of their fighters who had infiltrated the police and that the soldiers killed were British.

“One of our mujahideen, Atiqulla, who had infiltrated the police forces carried out the attack in Gereshk district in Helmand province today,” Taliban spokesman Qari Yousuf Ahmadi told AFP.

“He has killed two British soldiers”, Helmand governor Mohammad Naim Baloch confirmed the shooting had taken place in Greshk district and that two foreign soldiers were killed.

It was the second deadly incident in a week for Nato in Gereshk, also known as Nahr-e Saraj, after a British Royal Marine and army medic were killed while on patrol last Wednesday.

The Afghan conflict had seen a surge in insider attacks this year, with more than 50 Isaf troops killed by their colleagues in the Afghan army and police.

Nato said about 25 percent of the attacks were caused by Taliban infiltrators but the rest stemmed from personal animosities and cultural differences between Western troops and their Afghan allies.

In the most recent attack previously, two American soldiers were killed by a man in an Afghan police uniform in the central province of Uruzgan last Thursday.

The unprecedented number of so-called “green-on-blue” killings comes at a critical moment in the 11-year war, as Nato troops prepare to withdraw by the end of 2014 and hand responsibility for security to Afghan forces.

Nato top brass have admitted the seriousness of the phenomenon, with Isaf commander General John Allen saying that just as homemade bombs were the signature weapon of the Iraq war, in Afghanistan “the signature attack that we're beginning to see is going to be the insider attack”. US Defense Secretary Leon Panetta told a meeting of Nato defence ministers in Brussels earlier this month that countering the attacks was vital to success in Afghanistan.

Efforts to tackle the issue included orders that Nato soldiers working with Afghan forces should be armed and ready to fire at all times, even within their tightly protected bases, and the issuing of cultural guidelines.

The guidelines, drawn up by the Afghan defence ministry, urge their soldiers not to take offence if Nato colleagues exit the shower naked, swear or ask to see pictures of their wives.

The 28-page brochure tells Afghan soldiers these things are normal behaviour and no reason to open fire.

The insider attacks have added to growing opposition to the war in many Western countries providing troops to the US-led Nato opposition, with opinion polls showing a majority want their soldiers out as soon as possible.

Nato has said, however, that the attacks would not force it to bring forward its scheduled withdrawal of all combat troops by the end of 2014.