KABUL: An Afghan soldier shot dead a NATO colleague in the first "insider attack" of 2013, officials said Tuesday, as President Hamid Karzai prepared for crunch talks with Barack Obama.
More than 60 foreign troops were killed in 2012 in a surge of such attacks that have threatened to derail US-led efforts to train Afghan soldiers and police to take over the fight against the Taliban when NATO forces withdraw in 2014.
Monday's attack came as Obama prepared to host Karzai on Friday to discuss on long-term US military and civilian support for Afghanistan, where fears are growing that turmoil could erupt after NATO troops depart.
"An individual wearing an Afghan National Army uniform turned his weapon against International Security Assistance Force service members in southern Afghanistan yesterday, killing one," ISAF said in a statement.
A spokeswoman said the attacker was killed but gave no further details. It is ISAF policy to allow member nations to announce nationalities of dead troops.
The defence ministry in Kabul said the Afghan soldier opened fire in Helmand province, the heartland of the Islamist insurgency where US and British soldiers are fighting alongside the Afghan army.
A local police official said three ISAF soldiers were also wounded in the insider attack.
Taliban militants often claim insider attacks, but ISAF officials say most stem from personal grudges and cultural misunderstandings, more than a decade since the 2001 US-led invasion brought down the Taliban regime.
Karzai's relationship with Washington has been troubled in recent years and the issue of insider attacks is likely to be high on the agenda in Washington.
A White House statement said that Obama looked forward to discussing the "continued transition in Afghanistan, and our shared vision of an enduring partnership between the United States and Afghanistan".
The numbers of US troops who could remain in Afghanistan after NATO combat forces withdraw by the end of 2014 is likely to be a key theme of the meeting.
Latest reports citing the US Defense Department suggest between 3,000 and 9,000 troops would remain to focus on preventing Al-Qaeda, which was sheltered by the 1996-2001 Taliban regime, from regaining a foothold in Afghanistan.
General John Allen, commander of US and NATO forces in Afghanistan, had earlier suggested leaving 6,000 to 20,000 US troops, US media reports have said.
The number of foreign soldiers battling the Taliban-led insurgency has already fallen to 100,000 from about 150,000. Of those, 66,000 are US troops, down from a maximum of about 100,000.
Last month, in the first insider attack by a woman, a female police officer killed a US adviser in Kabul's police headquarters.
The threat has become so serious that foreign soldiers working with Afghan security forces are regularly watched over by so-called "guardian angel" troops on duty to provide protection.
Scores of Afghans have also died in similar attacks, with four policemen killed 10 days ago when a colleague let in attackers as officers slept at a post in the southern province of Uruzgan.
The policeman who aided the attack then fled with Taliban militants.