A roadside bomb killed two US-led coalition soldiers on patrol in Afghanistan, and a teenage Taliban suicide car bomber died ramming his taxi into a coalition convoy yesterday, wounding three coalition troops.

Another roadside bomb killed two Afghan soldiers and wounded four others in eastern Kunar province, General Zahir Wardak, a commander in the region, told Reuters.

The latest attacks come during the bloodiest period in an insurgency that has been raging since US-backed forces ousted a Taliban government from power in 2001.

Some 400 people were killed last month alone, as the Taliban have stepped up attacks in the south in an apparent attempt to weaken the resolve of Nato governments ahead of the handing of control to the group's peacekeeping troops in the southern provinces by the US-led coalition.

The car bomber struck the combat patrol just 15 kilometres north of Camp Salerno, the coalition's main base in Khost, a small mountainous province bordering Pakistan's militant infested tribal region of North Waziristan.

"The suicide attacker was a teenager. He was wearing new clothes, which is the sign he was dressed for the grave," said Rahmat Shah, a villager who witnessed the attack.

None of the coalition soldiers suffered life-threatening injuries, but a patrol in Nangahar, another eastern province, was less fortunate when it struck a roadside bomb.

Two coalition soldiers were killed, and another was wounded along with an Afghan interpreter travelling with them in a Humvee, while out on patrol in Khogyani district of Nangahar, a spokeswoman for the US military said.