Claiming responsibility, a Taliban spokesman told Reuters that the Islamists had used a van packed with 750 kg of explosives.

The attack was the deadliest strike against foreign troops in the heavily guarded capital since September 2009, when six Italian soldiers were killed by a car bomb. It comes after the Taliban announced a spring offensive against the Afghan government, foreign forces and diplomats in Afghanistan in response to NATO plans for an offensive on the group's southern stronghold of Kandahar.

The interior ministry said at least 12 Afghan civilians had been killed and 47 wounded. Most of the casualties were people waiting for a bus on the busy road near an army base, a government ministry and the parliament.

In a separate bomb attack, another member of the NATO-led International Security Assistance Force (ISAF) was killed in southern Afghanistan, ISAF said in statement, giving no other details.

Reuters