The suicide attack was followed by small arms and rocket fire near Puli Alam, the capital town of Logar province which is less than 100 kilometres (60 miles) south of the capital Kabul, Afghan and NATO officials said.

"There was an insurgent attack on coalition forces in east Afghanistan in which two service members were killed," a spokesman for NATO's International Security Assistance Force (ISAF) told AFP.

"It was a combination of a suicide bombing, small arms fire and rocket fire," he said.

Afghan officials in Logar said the attack started with a suicide car bombing. "The troops were defusing a bomb on the side of the road when they came under attack," provincial deputy police chief Rais Khan Sadiq told AFP.

NATO has about 112,000 troops in a US-led coalition fighting an insurgency by Taliban Islamists ousted from power in a 2001 invasion. They are due to withdraw by the end of 2014 and Afghan security forces, trained and equipped by NATO forces, will take charge of their country's security.