Afghan officials say Taliban insurgents attacked an army outpost in eastern Kunar Province, killing 20 soldiers.
The February 23 attack was said to be the deadliest single assault on security forces in months.
Kunar provincial governor Shuja Ul Mulk Jalala told RFE/RL's Radio Free Afghanistan at least eight soldiers were "taken hostage."
Defense Ministry spokesman Zahir Azimi said the attack in Kunar's Ghaziabad district near the border with Pakistan was carried out by "dozens" of Afghan and foreign fighters.
The Taliban claimed responsibility for the attack.
The office of President Hamid Karzai said the president postponed a planned two-day visit to Sri Lanka over the soldiers' killing.
It also said Karzai called on Pakistan to "take serious action to eliminate terror nests."
Afghanistan and Pakistan regularly accuse each other of harboring militants.
With reporting by Reuters, AP, and dpa