An Afghan woman and two children were killed and four other children injured as German soldiers opened fire on a civilian vehicle in the northern province of Kunduz, Afghan police said Friday.

The incident - which occurred south-east of the provincial capital, also called Kunduz - took place Thursday evening in a region where German troops lead operations for the NATO-led International Security Assistance Force (ISAF), Defence Ministry spokesman Thomas Raabe said in Berlin.

Two civilian vehicles approaching the checkpoint failed to heed clear signals from the troops manning the checkpoint and the security forces then opened fire, Raabe said.

Abdul Rahman Aqtash, security chief of the provincial police department, said the incident took place in Kharooti village, just outside Kunduz city.

"When the vehicle did not stop after several signals, the German forces opened fire at the car," Aqtash said, adding, "When the forces later checked the vehicle, they found two children and a woman dead and four other children wounded in the vehicle."

He said German, Afghan National Army and Afghan police forces installed the checkpoint in the area after receiving information that a vehicle would smuggle drugs into neighboring Takhar province.

"First, a vehicle approached the checkpoint but escaped when the forces tried to stop it," Aqtash said. "The forces opened fire at the second vehicle, which was driving behind the first one and did not heed repeated signals by the forces."

On Wednesday, a German soldier was killed in a roadside bombing in the Chardara district of Kunduz province. Three others were injured when a remote-controlled bomb blew up their armoured vehicle.

More than 3,500 German soldiers are serving in the ISAF and are mostly stationed in northern provinces. The ISAF has about 53,000 soldiers from about 40 countries in Afghanistan.