KABUL, Sept 30 (Reuters) - Special forces from the U.S.-led military coalition in Afghanistan fought insurgents early on Wednesday near the northern city of Kunduz, a spokesman said.

The forces were on a mission near the besieged Kunduz airport where hundreds of Afghan forces are based after retreating from the city, the first provincial capital to fall to the Taliban since 2001.

"Coalition special forces advisers, while advising and assisting elements of the Afghan Security Forces, encountered an insurgent threat in the vicinity of the Kunduz airport at approximately 1 a.m., 30 September," Col. Brian Tribus, a spokesman for the coalition, said.

"U.S. forces conducted an airstrike to eliminate the threat in Kunduz."

Tribus would not say what nationality the special forces were, but when asked if the statement meant they had engaged in combat, he said "Yes."

The rules of engagement for U.S. forces remaining in Afghanistan allow them to fight if they are threatened by insurgents.