Scores of heavily armed Taliban militants killed 13 Afghan soldiers in fierce clashes on Friday after storming an army post in the east of the country near the Pakistan border, police said.
More than 100 militants armed with rocket-propelled grenades and guns launched the attack in the Nari district of Kunar province, attacking the post from three directions before dawn.
"The attackers were heavily armed," a senior police officer in the district, who declined to be named, told AFP. "We have recovered the bodies of 13 of our soldiers, the outpost has been nearly destroyed."
The attack was finally pushed back after several hours when Afghan military and police reinforcements arrived. One soldier was severely injured, police said.
Defence ministry spokesman General Mohammad Zaher Azimi confirmed the attack but said that exact casualty figures were not available.
"We are still in the process of gathering information," he said.
Taliban spokesman Zabiullah Mujahid claimed responsibility for the assault in an email to AFP, and said that the militants had seized all weapons and ammunition from the remote post.
He added that 15 soldiers had been killed.
The border region between Afghanistan and Pakistan is a key battleground in the fight against the militants, many of whom use safe havens inside Pakistan to launch attacks against Afghan soldiers and the US-led military coalition.
For years, leaders in Kabul and Islamabad have traded accusations of blame over the Islamist extremists who pose a threat to security in both countries and criss-cross the porous border with impunity.
Pakistan was an ally of the Taliban until joining the US-led "war on terror" after the September 11, 2001 attacks and has been accused of tacitly or actively supporting the insurgents.
Pakistani officials vigorously deny the allegations, but rebel bases in Pakistan infuriate Afghan President Hamid Karzai and remain a major obstacle to peace as US-led troops prepare to pull out of Afghanistan by the end of 2014.
There are presently around 100,000 international troops fighting the insurgents, with Afghan soldiers and police gradually taking over security responsibilities ahead of the withdrawal.
Kunar province has seen some of the fiercest clashes in the country over recent years as fighting spread from the southern hotspots of Helmand and Kandahar to the eastern border regions.
A NATO air strike in the province on Sunday killed 11 children, officials said, when air support was called in after local and coalition forces came under attack.