KABUL - Twenty-one civilians and four police officers were killed Thursday in a car bombing in the central Afghan province of Logar, while two NATO soldiers and 15 militants were killed in the southern region, officials said.

‘Twenty-one local civilians, including school students, and four of our police officers were killed in the blast,’ said General Mustafa Andarabi, the provincial police chief.

The explosives were placed in a truck that had apparently been overturned purposely on a road in the village of Sheikhak in Mohammad Agha district.

‘As the local people and police were trying to remove the vehicle from the road, the explosives which were hidden inside were detonated by a remotely controlled device, causing a massive blast,’ Andarabi said.

The attack, which took place about 30 kilometres south of Kabul, also injured four civilians, including three children, Andarabi said.

Several shops in the main market of Mohammad Agha district were destroyed and windows of houses were smashed as far as one kilometre away, a police official said.

Footage from the scene by Tolo, a private TV channel in Kabul, showed the explosion left a huge crater in the road, while mangled and charred parts of vehicles were seen scattered around.

Mohammad Asif Nang, a spokesman for the Afghan Education Ministry, said that several students from a nearby boys school were killed in the attack.

Afghan President Hamid Karzai condemned the attack, which was the deadliest single incident carried out by anti-government elements since the beginning of this year, and ordered the security forces to bring to justice the perpetrators of the ‘unforgivable crime.’

‘No Muslim commits such a barbaric and cowardly act, targeting civilians against all Islamic and human values,’ Karzai said in a statement issued by his office.

No group immediately took responsibility for the bombing.

Taliban militants, who were driven from power in a US-led invasion in late 2001, have waged a bloody insurgency against the Western-backed Afghan government and its international military allies. They rely heavily on use of suicide and roadside attacks as part of their campaign.

In another incident, two NATO-led International Security Assistance Force (ISAF) soldiers were killed in a roadside bomb blast in the southern region on Wednesday, the alliance said in a statement on Thursday.

The statement did not reveal the nationalities of the soldiers, nor did it say where exactly in the southern region the incident took place. Most of the forces stationed in the region are from the US, Canada, Britain and the Netherlands.

In another incident in the same region, 15 Taliban militants were killed and several others wounded after they attacked government buildings in Suri district of Zabul province early Thursday, Abdul Rahman Sarjang, the provincial police chief said.

There were no casualties among the joint Afghan and NATO forces, who took part in the gun-battle, Sarjang said, adding that the forces detained one militant during the fighting.

The southern provinces are the most volatile region in the country. Some 4,000 newly-deployed US Marines and more than 600 Afghan soldiers and police are taking part in an operation, dubbed Khanjar or Strike of the Sword, in Helmand province to drive the militants from several districts before August 20 presidential elections.

The Afghan Defence Ministry said on Wednesday that the combined forces have so far killed 27 insurgents since the start of operation on July 2, and have taken control of one district from the Taliban militants, who still hold at least three more districts.