KUNDUZ, Afghanistan - A NATO air strike mistakenly killed seven Afghan police and wounded two others on Thursday, hospital and government officials said, adding to strains on the alliance.
The NATO-run International Security Assistance Force ordered an immediate investigation into the incident in the northern province of Kunduz, where Taliban violence has recently increased, and hailed the role played by Afghan forces.
The incident occurred when a joint patrol by the Afghan army and police and NATO forces came under Taliban attack in the Imam Sahib district, Afghan interior ministry spokesman Zemarai Bashary told AFP.
NATO called in an air strike and "the Afghan forces were bombed by mistake," the spokesman said. "Seven policemen were killed, including two officers, and two policemen were wounded."
Civilian casualties are a sensitive issue in Afghanistan, as President Hamid Karzai's government and his Western backers attempt to win a war of perceptions while battling an eight-year insurgency.
The director of the main hospital in Kunduz, Noor Ull-Haq Hakimi, confirmed that the bodies of seven policemen were brought in as well as two wounded policemen. The local government confirmed the incident without giving details on casualties.
"ISAF and Afghan authorities will conduct an immediate, thorough joint investigation," the NATO-run force said in a statement.
It confirmed that an air strike was called in in response to an attack in Imam Sahib but said an initial assessment had revealed no casualties.
"Subsequently, ISAF was advised by the Afghan national police command centre that they received a report that several Afghan police were killed and wounded in this operation," ISAF said.
"Afghan national security forces are critical to the security of this nation and the loss of a single Afghan life affects all of us," said Lieutenant General David Rodriguez in the statement.
"We have committed to our Afghan partners every resource available to investigate this incident."
In southern Afghanistan 15,000 US, NATO and Afghan forces are pressing on with a major offensive against a Taliban bastion. Commanders say progress has been slowed by hidden bombs and militants hiding behind human shields.
The United States and NATO have more than 120,000 troops fighting the insurgency, with the number set to rise to 150,000 by August under President Barack Obama's surge, most of them being deployed to the troubled south.
Despite measures to avoid harming civilians -- such as an order by US General Stanley McChrystal, commander of foreign troops, to limit air strikes -- at least nine civilians were killed by a NATO rocket strike on Monday.