An attacker in an Afghan army uniform killed a member of the  International Security Assistance Force in southern Afghanistan Sunday, the force said.

"An individual in an Afghan National Army uniform turned his weapon against ISAF service members, killing one," an ISAF spokesman said, declining to give the victim's nationality.

Mohammad Zarak, spokesman for the governor of Helmand province, said  the shooting took place in Nad Ali district after an argument between an Afghan soldier and coalition forces.

At least ISAF soldiers have been killed in insider attacks this year, undermining trust between coalition and Afghan forces as NATO prepares to withdraw most combat troops by the end of 2014.

Meanwhile. a mother and her newborn baby were among six family members killed in a roadside bombing in eastern Afghanistan overnight, police and witnesses said Sunday.

The victims were heading home from the hospital after the mother had given birth when the bomb planted by Taliban insurgents tore through their vehicle in Khost province on the Pakistan border, police told AFP.

"Six people -- three women, two adult men and a newborn baby -- were killed," deputy provincial police chief Mohammad Yaqoub said.

Relatives said the family was returning home after the mother delivered her baby in hospital in the town of Sabari.

Five other civilians were killed in two separate roadside bomb blasts in the southern province of Kandahar Sunday, President Hamid Karzai's office said in a statement offering condolences to the families of all those killed.