At least 19 soldiers have died after the Afghan Taliban attacked an army outpost in eastern Kunar province.
Defence Ministry spokesman Zahir Azimi, in a posting on his Twitter feed, said 19 soldiers were killed, and two wounded, in Kunar's Ghaziabad district.
The Taliban later issued a statement claiming responsibility.
Abdul Ghani Musamem, spokesman for the provincial governor, said seven soldiers were captured by the Taliban in the attack in a remote, mountainous area near the border with Pakistan.
He said Afghan forces had begun an operation to try to free the captured soldiers.
Provincial governor Shujah-Ul Mulk Jalala said some of the soldiers in the post were thought to have aided the attackers.
However, this could not be verified by an independent source and the Taliban did not mention insider help in their statement.
The Defence Ministry did not immediately confirm the report of captured soldiers.
Casualties among Afghan soldiers and police have increased in recent years as they take more responsibility in the fight against insurgents before their Western allies, the US and NATO troops, leave under a US plan by the end of the year.