France is suspending military operations in Afghanistan, French President Nicolas Sarkozy said on Friday, after confirming that four soldiers killed there were French.
An Afghan intelligence security source said earlier that four soldiers were killed and 17 wounded by an Afghan soldier in the Taghab valley of eastern Kapisa province.
The shootings were the latest of several in which western soldiers have been killed by members of the Afghan security forces, undermining trust between Afghan and western troops in the runup to the withdrawal of foreign combat troops in 2014.
The four deaths take to 82 the number of French soldiers killed in Afghanistan since 2001.
Nato said in a statement that the suspected shooter had been apprehended, but disclosed no details about the incident.
Similar attacks have raised fears of increased Taliban infiltration of the Afghan police and army as Nato speeds up the training of the security forces. In some cases the attackers were Afghan soldiers who turned on Nato troops. Others involved insurgents dressed in Afghan uniforms.
Earlier this month, a US troop was killed when a man in an Afghan army uniform opened fire at a base in the south of the country.
In one of the worst incidents, a veteran Afghan military pilot opened fire at Kabul airport on April 27, 2011, killing eight US troops and an American civilian contractor.