An Afghan policeman poisoned and then shot dead nine of his colleagues while they were sleeping early Friday in the eastern province of Paktika, police and provincial government officials said.
It was the latest in a series of shootings by Afghan security personnel of their local and foreign colleagues, deaths that have ramped up tensions between the allies even as NATO-led forces prepare to pull out by the end of 2014.
Paktika provincial police chief Dawlat Khan said the shooting happened before dawn in Yahyakhil district.
"A local policeman named Asadullah was persuaded by Taliban insurgents to carry out the firing inside the security check post," he told AFP.
"First he poisoned his colleagues and then later he woke up for night duty at 3:00 am. Then he used his assault rifle to kill his nine colleagues. They were sleeping inside the post."
Asadullah fled the scene after the shooting and is on the run, he added, and there were no survivors.
Mokhlis Afghan, spokesman for the Paktika governor, confirmed the attack and that one policeman had fled, adding that two others had been arrested.
Earlier in March, another nine Afghan police were killed, in the southern province of Uruzgan, in an insurgent attack that authorities said was believed to have been facilitated by a fellow officer and suspected Taliban infiltrator.
The gunman in Friday's attack and his victims belong to the so-called local Afghan police, militias that form part of the government's security forces but do not come under the national police set-up.
Paktika is a hotbed of the Haqqani network, essentially a faction of the Taliban allied to Al-Qaeda, and neighbours Pakistan's tribal belt, which Washington considers to be a global hub of Al-Qaeda and Taliban militants.
The Taliban, who have been fighting an insurgency against Hamid Karzai's government in Kabul and its Western allies for more than a decade, claimed responsibility for the attack.
Spokesman Zabihullah Mujahid said in a text message to AFP: "Last night, a mujahid fighter attacked a security check post. As a result, he killed nine puppet local policemen.
"The mujahid fighter has managed to escape and joined the Taliban ranks."
Members of both Afghan units and NATO's US-led International Security Assistance Force (ISAF) have been targeted by Afghan security personnel in a series of attacks this year.
So far this year 17 foreign troops, including at least seven Americans and five French trainers, have been killed in such shootings, more than one in six of the 93 ISAF fatalities since January 1.
The attacks threaten to undermine efforts to train Afghan troops to take over security for the entire country ahead of ISAF pulling out by the end of 2014, the cornerstone of the West's strategy in Afghanistan.
Relations between the allies have also been strained by a video of troops urinating on Taliban corpses, the burning of Korans at a US military base and a massacre of civilians by a US soldier who has been charged with 17 murders.
NATO troops have been ordered to adopt strict new security precautions to counter the threat.
ISAF commander US General John Allen ordered some advisers to carry weapons and for NATO units to designate one team member as a "guardian angel" to stay armed and on alert for possible fratricidal attacks, officials said.
Coalition troops working at Afghan government or military buildings are required to move desks to make sure their backs do not face the door.
Officials say that despite Taliban claims to the contrary, most of the attacks are not by Taliban infiltrators but by "self-radicalised" individuals, with cultural differences sometimes playing a part.
Underlining that it is not only foreign troops who are targeted, five policemen were poisoned and shot in the city of Kandahar in February, with their cook fleeing and their guns missing.
Elsewhere in Afghanistan, NATO's US-led force announced the deaths of two soldiers in the south on Thursday, one in a bomb blast and a second in an insurgent attack.