A powerful blast has targeted a NATO military convoy in Afghanistan's capital Kabul, killing two people and wounding 26 others, including women and children, officials have said.

The blast on Tuesday came on the main road to the airport, around 500m from the US embassy and near a base for foreign troops.

The armed group Taliban has claimed responsibility for the attack.

NATO said none of its troops were killed or injured in the attack.

"It was a suicide car bomber targeting a convoy of foreign forces in Kabul," interior ministry spokesman Sediq Sediqqi said.

Kabul deputy police chief Sayed Gul Aga Rohani confirmed the attack and said there were casualties, but no further details were immediately available.

Al Jazeera's Jennifer Glasse, reporting from close to the scene of the explosion, said the "huge" bombing explosion was heard around the city.

"Police and the army are already on the scene keeping people away... We heard the blast from our office, about 1.5km away and saw a huge plume of smoke," Glasse said, adding civilian cars had been caught up in the explosion.

The blast came about a week after the Taliban staged an attack on the Afghan parliament in Kabul, killing at least five people.

Also on Tuesday, a suicide attack on the police headquarters of a southern province killed three people and wounded more than 50, including policemen, Afghan officials said

Omar Zawak, spokesman for the governor of Helmand province, said most of the injured in the attack were women and children.

Police spokesman Farid Hamad Obaid said a car packed with explosives was driven into the back wall of the police headquarters in an attempt to breach a gate.

Afghan security forces arrived in time to prevent fighters from entering the compound, he says. Blaming the Taliban, he says all the gunmen fled the area.

In eastern Paktya province, three people were killed and one wounded when their vehicle hit a roadside mine, said the provincial police chief Zalmai Oryakhel.

On Sunday, at least 11 Afghan soldiers were killed in a Taliban ambush in Herat province in western Afghanistan.

Security forces are facing their first fighting season without NATO combat support.