Afghan and NATO-led forces killed or wounded more than two dozen insurgents in a 21-hour battle in the northeast of the country close to the border with Pakistan, the alliance said on Saturday. The clash began when troops from the Afghan army and the NATO-led International Security Assistance Force (ISAF) attacked a group of fighters in the Watapoor district of Kunar province late on Thursday as they were massing to attack an ISAF base. "Small arms, machineguns, mortars, artillery, attack helicopters and close-air support with precision guided munitions were all used during the engagement," the statement said. Most ISAF troops in eastern Afghanistan are American.Allied fighters belonging to the Taliban, former Afghan Prime Minister Gulduddin Hekmatyar's Hezb-e Islami and al Qaeda are all active in Kunar province, a heavily wooded, mountainous province which borders tribal areas of Pakistan. The rough terrain made it difficult to confirm rebel casualties, ISAF said, but "based on intelligence reports received through a number of sources, insurgent losses are estimated at more than two dozen killed or wounded." There were no casualties among Afghan or ISAF troops or civilians, it said.