Kabul, Afghanistan (CNN) -- A coalition operation against militants in southeastern Afghanistan has left at least 50 insurgents dead as Afghan and NATO forces swept through a "known Haqqani network" area.

The encampment was considered a staging ground for Haqqani and foreign fighters, NATO's International Security Assistance Force reported Friday.

The Haqqani network is an insurgent group loosely affiliated with the Taliban, and is believed to be based in Pakistan's lawless frontier territories. They operate along the porous Afghan-Pakistan border regions.

The group has been responsible for "several high-profile attacks against the Afghan government and its citizens," ISAF reported.

The coalition operation -- which included Afghan special forces -- engaged "multiple groups of insurgents," who were armed with rocket-propelled grenade launchers and heavy machine guns.

The firefight took place against multiple insurgent groups, who were holed up in areas that included caves and fortified bunker positions, ISAF reported.

The operation spanned night-time hours as NATO airstrikes pummeled insurgent positions.