KANDAHAR, Afghanistan - A civilian car hit a freshly planted land mine in southern Afghanistan on Thursday, killing six people and wounding six others, and Taliban militants beheaded a woman they accused of spying and her grandson, officials said.

The blast ripped through the car as it traveled on a road outside the town of Tirin Kot, in Uruzgan province, a ministry statement said.

"This mine was possibly planted by the enemy," it said. Afghan officials refer to the Taliban and other militants as "the enemy."

Militants usually plant mines and other roadside bombs to target foreign and Afghan troops, but most of the victims in such attacks have been civilians.

In Uruzgan's Dihrawud district, Taliban militants beheaded a 60-year-old woman and her grandson on Wednesday, said provincial police chief, Juma Gul Himat. The militants accused the woman of spying for government and NATO forces.

The incidents follow a roadside blast Wednesday on a NATO convoy in eastern Afghanistan that killed two soldiers and wounded three others, the alliance said in a statement.

NATO did not disclose the nationalities of the dead and wounded or the location of the attack. However, most of the NATO troops in the east are American.

This year has been the deadliest since the U.S.-led invasion in 2001. More than 6,200 people have been killed in insurgency-related violence, according to an Associated Press tally of figures from Western and Afghan officials.