NATO mistakenly killed six of its Afghan army allies in an airstrike Wednesday while the Afghans were attacking insurgents in the country's east, officials said.
While the Afghan ministry blamed the attack on the Taliban, the Afghan defense official condemned the latest "friendly fire" deaths, which came at a time when international troops are trying to improve coordination with Afghan security forces in hopes of handing over more security to them nearly nine years into the war.
Three American soldiers were also reported killed Wednesday in a roadside bomb in the south.
The air strike was originally aimed at Taliban militants in the restive province in south-central Afghanistan, Ghazni, said Nawruz Ali Mohamoodzada, a provincial police official.
The incident took place late Tuesday, he said.
"It mistakenly hit an army post in which six soldiers were killed. An investigation has been launched," he added.
A Coordination problem
The Afghan Defense Ministry spokesman Gen. Mohammad Zahir Azimi said that the Afghan soldiers were launching an ambush before dawn against insurgents in Ghazni when NATO aircraft began firing on them without warning,
However, five Afghan soldiers were killed he said, and two more were wounded in the airstrike in Ghazni's Andar district.
"This is not the first time such an incident has happened, but we wish that at least this would be the last one," Azimi said.
NATO spokesman Josef Blotz confirmed the botched airstrike. He said he regretted the Afghan National Army deaths, telling a news briefing that a joint investigation has been launched.
"The reason for this is perhaps a coordination issue," Blotz said. "We were obviously not absolutely clear whether there were Afghan national security forces in the area."
He extended the personal condolences of U.S. Gen. David Petraeus, the newly arrived commander of NATO forces in Afghanistan, to the families of the victims.
Petraeus has backed the White House in withdrawing troops from Afghanistan starting July 2011, however not on a wider scale if the situation is not untenable.
The Afghan soldiers' deaths at the hands of their allies was another setback in the U.S.-led force's goal of training and coordinating with the Afghans, one of the cornerstones of its counterinsurgency strategy.
NATO is counting on the strategy to beat back the insurgents' recent gains, nearly nine years after U.S.-backed forces toppled the Taliban's hard-line Islamist regime. The aim is to win over the population by limiting Afghan casualties while securing new areas, eventually turning control over to local army and police and allowing foreign troops to withdraw.
Violence has been increasing across Afghanistan, coinciding with the arrival of thousands of American soldiers for a new push to try to establish Afghan government control in the south, one of the Taliban's strongest areas of influence.
Western forces have killed scores of Afghan civilians and friendly soldiers, mostly in air strikes that were aimed at insurgents.
Afghan soldiers have also been responsible for the deaths of NATO soldiers in the past.
Separately, four Afghan police officers were killed by a bomb in Logar, another restive region just south of Kabul, the interior ministry said.
The officers were on patrol in a troubled part of the province when the bomb hit their vehicle Tuesday.