A suicide bomber blew himself up among Afghan soldiers in eastern Afghanistan on Friday, killing four troops and a child, government officials said.
The extremist Taliban movement, responsible for a wave of suicide attacks across Afghanistan, said one of its men carried out the blast in the eastern province of Khost.
The bomber, who was on foot, blew himself up near a military vehicle on a main road about 25 kilometres (15 miles) from the border with Pakistan, they said.
Four soldiers were killed and four wounded, Defence Ministry Spokesman General Mohammad Zahir Azimi told AFP. He did not know about civilian casualties.
A spokesman for the Khost government, Khaibar Pashtun, said a child was killed and three civilians wounded.
Taliban spokesman Zabihullah Mujahed told media that his group was responsible for the attack. He also said four soldiers were killed.
The extremist group was in government between 1996 and 2001, when it was removed in a US-led campaign for harbouring Al-Qaeda leaders after the 9/11 attacks.
The rebel movement, which has sanctuaries in Pakistan, makes heavy use of suicide attacks and other bombings. Most attacks target the Afghan and international security forces, but they kill far more civilians.
Insurgent attacks killed about 300 civilians in the first four months of this year, a UN special rapporteur said last week.
Decades of war had left Afghanistan in ruins by the time the Taliban were ousted. The country's recovery is being aided by a host of nations.
About 70,000 international soldiers are also helping the government to fight a tide of extremist violence and rebuild the Afghan security forces.
A US general leading efforts to build and train local forces said on Thursday that Afghanistan's army would need international air support in combat operations for another five years.
US Major General Robert Cone, speaking to reporters at NATO headquarters in Brussels, said the support would have to continue until the fledgling Afghan air force was fully operational, probably in 2013.
Cone also said the Afghan army now numbered about 57,000 troops, with 9,000 others in training, and that it remained on target to meet a requirement for 80,000 personnel early next year.