A weekend clash that left eight US soldiers dead also killed more than 100 Taliban fighters, NATO's International Security Assistance Force (ISAF) said on Tuesday.
"A more detailed battlefield assessment following the October 3 attack in Nuristan has determined that enemy forces suffered more than 100 dead during the well-coordinated defence -- significantly higher losses than originally thought," a statement said.
Hundreds of militant fighters on Saturday swept down a remote hillside at dawn near the mountainous border with Pakistan to attack two Afghan army and NATO outposts.
The resulting firefight lasted into the night and prompted US troops to call in air strikes.
The loss of eight US soldiers was NATO's biggest loss of life in a single incident since 10 French soldiers were killed in an ambush, also in eastern Afghanistan, in August 2008.
Two Afghan soldiers and a police officer also lost their lives in the weekend attacks, for which the Taliban claimed responsibility.
Some 13 police officers and two Afghan journalists working for a radio station set up with US help were captured, local officials said.
ISAF said on Tuesday the attack was conducted by "local anti-Afghan forces", possibly helped by the Taliban Hizb-i-Islami militia of Pashtun warlord and anti-American former Afghan Prime Minister, Gulbuddin Hekmatyar.