The Taliban claim the Afghan soldier who shot dead four French soldiers at a base east of Kabul, prompting France to threaten to withdraw early from the country, was one of their recruits.
Taliban spokesman Zabihullah Mujahid said the gunman was an infiltrator working for the Taliban, also known as The Islamic Emirate of Afghanistan.
"The Islamic Emirate of Afghanistan has recruited people in important positions," he said. "Some of them have already accomplished their missions."
French officials said an Afghan man in army uniform suddenly turned and opened fire on unarmed French soldiers during a sports training exercise on Thursday, killing four and wounding 16 others.
French president Nicolas Sarkozy suspended all military operations on the ground, and sent his defence minister, Gérard Longuet, to Kabul to investigate whether conditions were safe enough for French troops to continue to operate.
The shooting, which took the French death toll to 82 since the war began, is the latest of several attacks in which western soldiers have been killed by members of the Afghan security forces in the run-up to the withdrawal of foreign troops in 2014.
France currently plays an important role in training the new Afghan national security forces. A sudden withdrawal could result in a major setback for the US-led Nato coalition, particularly if other countries follow suit.
"If the security conditions are not clearly established then the question of an early return of French forces from Afghanistan will arise," Sarkozy said on Friday. "The French army is in Afghanistan at the service of the Afghans, against terrorism and against the Taliban. The French army is not in Afghanistan so that Afghan soldiers can shoot at them."
The French defence minister described how the attacker opened fire on unarmed French soldiers inside their base in the Tabhab valley of Kapisa province while the troops were on a difficult training exercise at high altitude.
The gunman was arrested and was being questioned.
Allegations of abuse by western forces, such as a video apparently showing US marines urinating on corpses, have bolstered support for the Taliban among Afghans and could lead to more violence, according to a regional commander of the Islamist militant group.
"Our missions have become easier because of incidents like the video," he said.
The latest shooting came just weeks after an Afghan army soldier, who was being trained by French troops, gunned down two members of the Foreign Legion. French forces fired back and killed him.
The French foreign minister, Alain Juppé, said: "It is incomprehensible and unacceptable that soldiers in the Afghan army murder French soldiers."
