GHAZNI - Taliban attacks across Afghanistan killed at least 15 people on Wednesday, including four policemen and three civilians who died when insurgents tried to storm a joint NATO-Afghan military base.

A suicide car bomb was detonated at the entrance of the base in the eastern province of Ghazni, one of the heartlands of the 12-year Islamist insurgency against NATO-led foreign troops and the Kabul government. Eight to ten gunmen then tried to enter the camp from two directions in a firefight that lasted about one hour, Ghazni deputy governor Mohammad Ali Ahmadi told AFP.

He added that at least one attacker had been gunned down inside the base, and that several Polish soldiers were wounded during the fighting. The base in Ghazni houses the provincial reconstruction team (PRT), one of the units that deploys NATO military and civilian staff to help Afghan development projects.

NATO’s International Security Assistance Force (ISAF) was not able to immediately comment on the attack or Polish injuries. Poland, which has 1,200 troops in Afghanistan, is the lead ISAF nation in Ghazni. “Seven people including four policemen have been killed,” provincial hospital chief Baz Mohammad Hemat told AFP. “Of 34 injured, five of them are police forces and the rest are civilians including women and children.”

Foreign troops are withdrawing from Afghanistan as local security forces take over responsibility for thwarting the Taliban, who are strongest in eastern and southern provinces such as Ghazni, Helmand and Kandahar.

Afghan and international leaders are trying to open peace negotiations with the militants to halt the conflict before a presidential election in April and the departure of all NATO combat troops by the end of the year.

Taliban spokesman Zabiullah Mujahid claimed responsibility for the Ghazni strike in an emailed statement, and said that attackers had successfully entered the base.

Also on Wednesday, another suicide bomber rammed his explosives-laden car into a convoy of NATO troops in Helmand, killing four civilians. About 15 bystanders were injured in the attack on NATO forces travelling in heavily-armoured vehicles on a main road in Lashkar Gah, the capital of volatile Helmand.

“Four civilians were killed and 15 wounded,” provincial spokesman Omar Zuwak told AFP.

There were no confirmed military casualties, and ISAF declined give any details.

About 87,000 international troops are deployed in Afghanistan to fight the Islamist insurgency that erupted after the hardline Taliban regime was ousted from power in 2001.

Elsewhere in Afghanistan on Wednesday, four drivers were killed and 40 trucks carrying NATO fuel supplies set ablaze when a rocket was fired at a parking lot in the western province of Farah.

The provincial spokesman blamed the Taliban for the attack on trucks that had parked for the night to avoid using the dangerous highway in the dark.

According to a recent United Nations report, civilian casualties in the Afghan war rose 23 percent in the first half of this year due to Taliban attacks and increased fighting between insurgents and government forces. The Taliban have increased attacks during the summer fighting season as newly-trained Afghan soldiers and police take over from NATO forces, but the insurgents have made no significant territorial gains.