France says it is suspending all training and joint operations in Afghanistan after an Afghan soldier shot dead four French troops.

President Nicolas Sarkozy also says he is considering an early withdrawal of French troops from Afghanistan if security conditions “are not clearly established,” following Friday's attack.

Afghan security officials said at least 16 other people were wounded in the assault in the eastern Afghan province of Kapisa.

French Defense Minister Gerard Longuet said the French troops were unarmed when the attacker opened fire during a training exercise at a base jointly operated by French and Afghan forces. The shooter has been apprehended.

Friday's incident is the latest of several attacks in which international troops have been killed by Afghan security forces.

In December, an Afghan soldier opened fire and killed two members of the French Foreign Legion in Kapisa. And earlier this month, an Afghan soldier shot and killed an American service member in Zabul province.

Friday's deaths bring the number of French troops killed in the Afghan war to 82. France has about 3,600 soldiers serving in Afghanistan, mainly in the east, with all combat troops set to leave the country in 2014.

President Sarkozy said Friday that it was “unacceptable” that Afghan troops would attack French soldiers. He said Defense Minister Longuet and France's army chief of staff are traveling to Kabul Friday to determine the circumstances behind the attack and will report back on how to proceed.

Afghan President Hamid Karzai expressed his condolences. NATO Secretary-General Anders Fogh Rasmussen said it was a “sad day” for international troops in Afghanistan and the French people, but insisted such incidents are “isolated.”

The New York Times on Friday cited a classified coalition report, which says such attacks are motivated by deep-seated animosity between the forces that are supposed to be allied. The report says ill will and mistrust run deep among civilians and militaries on both sides.

But NATO spokesman U.S. Lieutenant General Jimmie Cummings, Jr. said Friday that incidents where Afghan soldiers have wounded or killed coalition members are isolated cases and are “not occurring on a routine basis.”

Cummings added “we train and are partnered with Afghan personnel every day and are not seeing any issues or concerns with our relationships.”

Meanwhile late Thursday, a coalition helicopter crashed in southern Afghanistan, killing six U.S. Marines.

A NATO spokesman said there was no insurgent activity reported in the area when the helicopter went down.

The cause of the crash is being investigated.