The NATO military alliance confirmed the killing of the foreign servicemen, but it did not provide further details about the nationalities of the slain soldiers and the exact location of the incident.
More than 260 soldiers, mostly American forces have lost their lives in militant attacks in war-torn Afghanistan so far this year.
A total of 566 US-led forces died in Afghanistan in 2011. However, 2010 remains the deadliest year on record for foreign military casualties, with a death toll of 711.
The high number of military casualties in Afghanistan has intensified opposition in the United States and other NATO member states to the protracted war in the country.
Insecurity continues to rise across Afghanistan, because the presence of thousands of US-led forces in the country ten years after the beginning of the US-led war in 2001
The US-led war in Afghanistan, with civilian and military casualties at record highs, has become the longest military conflict in the American history.