US-led troops in Afghanistan have killed up to 24 Afghan fighters who attacked a coalition convoy in southern Afghanistan overnight, the US military says.
There have been a spate of attacks on US forces in the area
The exchange happened near the town of Spin Boldak on the Pakistani border.
A statement said coalition forces engaged the attackers, killing approximately five of them.
It said up to 19 more fighters were killed as AH-64 Apache helicopters were called in as air support to raid the surrounding hills. No coalition casualties were reported.
Earlier, a local Afghan commissioner told the BBC that a group of about 100 fighters suspected to be loyal to Afghanistan's former rulers, the Taleban, crossed the border from Pakistan on Saturday night.
The commissioner, Fazluddin Agha, said five were captured.
If confirmed, the fighting would be the bloodiest in Afghanistan since June, when government forces reported killing 40 suspected Taleban fighters in the Spin Boldak area.
Attacks on increase
The attack happened near a US base in the town, the US statement from Bagram Air Base said.
"The coalition forces drove through the kill zone, requested close air support and engaged the enemy forces, killing approximately five enemy and pursuing the remaining forces into the surrounding hills," it said.
"AH-64 Apaches provided the air support, making several passes on the hill, killing approximately 17-19 more enemy," the statement added.
In the last few days, there have been a number of attacks on the coalition troops and allied Afghan militias in the south-east, in which eight members of the militia were killed.
Afghan officials accuse former Taleban members of carrying out attacks, saying that they are getting help from groups in Pakistan.
Pakistan says it is doing all it can to seal the two countries' long and porous border.