Nine troops of the NATO-led ISAF force died Sunday in a heavy fighting with militants in eastern Afghanistan as the war-battered nation has been the scene of increasingly fierce counter-insurgency battles.

Fifteen soldiers of the International Security Assistance Force (ISAF) and four Afghan National Army (ANA) soldiers were also wounded in the firefight which began early morning in Dara-I-Pech district of Kunar province, the ISAF said.

The fighting continued into the day as insurgents were repulsed from a combined ISAF and ANA combat outpost they attacked, it noted in a statement.

"Although no final assessment has been made, it is believed insurgents suffered heavy casualties during several hours of fighting," the NATO-led military said.

The rebels relied on small arms, machine guns, rocket-propelled grenades and mortars to attack while the ISAF and ANA responded with small arms, machine guns, mortars, artillery, close air support and helicopters, it added.

The military alliance did not disclose the nationalities of the fallen soldiers in its statement but reports reaching here said they were U.S. troops.

America has contributed over 23,000 troops to the 52,000 NATO- led forces which are deployed across Afghanistan with a UN authorized mission of stabilizing security and helping in reconstruction.