Four policemen were killed when two suicide attackers disguised in uniform blew themselves up inside a police headquarters in eastern Afghanistan on Saturday, the provincial governor said.
Eleven other officers were wounded when the attackers detonated their explosives in the main police base in Sharan, the capital of Paktika province, which shares a border with Pakistan, governor Muhibullah Samim said.
"Two suicide bombers wearing police clothes entered the police headquarters and blew themselves up. Four people were killed and 11 were wounded," he said, adding that an investigation had be opened to find out how the bombers entered the building.
Provincial spokesman Mukhlis Afghan said all the dead and wounded were policemen.
President Hamid Karzai issued a statement condemning the attack, blaming it on "the enemies of the country".
Taliban insurgents principally use suicide attacks and home-made bombs to attack government forces and more than 140,000 US-led troops fighting a counter-insurgency campaign mostly in the south and east of the country.
Paktika province is deeply embroiled in the rebels' campaign to return to power as it lies across the border with Pakistan's tribal area of South Waziristan, believed to be the base for the Taliban-allied Haqqani network.
A suicide attack by a Jordanian triple agent at the CIA base in neighbouring Khost province last December killed seven Americans and his Jordanian handler, marking the CIA's worst loss in a single day in more than 25 years.
The police are seen as central to the goal of getting the Afghan authorities to take the lead in the fight against the Taliban, who were ousted after the US-led invasion in late 2001 but who continue to wage a deadly guerrilla war.
There are currently about 80,000 police officers and US and NATO forces hope to bring that number up to 134,000 by October next year, alongside the 170,000 personnel planned for the army by the same date.
US military leaders back the government's plan for the Afghan police and army to assume responsibility for security by 2014, with the timetable agreed at a landmark NATO summit in Lisbon this month.
NATO's International Security Assistance Force on Friday killed three Taliban commanders and arrested one other in the southern town of Ghazni, in the province of the same name, provincial police chief Delawar Zahid told AFP.
"The operation took place in Ghazni town at half past midnight and the troops arrived by helicopter and killed the commanders with gunfire," he said.
In another coalition operation in eastern Nangarhar province, ISAF forces said they targeted a Taliban commander in a bomb strike and killed 18 militants, including the commander.
Local district chief Haji Mohammad Hassan confirmed the incident.
The coalition later announced that one of its troops had been killed in a bomb attack in eastern Afghanistan, bringing to 662 the number of foreign service personnel who have lost their lives this year, according to an AFP tally based on that tracked by the independent icasualties.org website.
The toll is the highest since the US-led invasion in late 2001. Last year 521 NATO soldiers died.
The number of ordinary Afghans killed in the conflict rose by a third in the first six months of 2010 to 1,271, with most deaths caused by insurgent attacks, the UN said in August.