Nato says a person wearing an Afghan national security force uniform shot dead three civilian contractors working with the coalition
Five Nato service members have been killed in roadside bombings in Afghanistan during the past two days, while Afghan officials reported that four civilians died when hundreds of shells and rockets were fired from neighbouring Pakistan.
The artillery shells hit homes along frontier areas from which insurgents have in the past staged cross-border attacks.
The Afghan government has not yet openly blamed the Pakistani military for the artillery barrage, which reportedly hit districts in the eastern provinces of Nuristan and Kunar.
Both are considered insurgent hotbeds, and militants allied with both the Afghan and Pakistani Taliban regularly cross the mountainous border in both directions.
All five of the Nato service members were killed in roadside bomb attacks - one on Saturday in the east, two in the east and two in the south on Sunday.
The deaths bring the number of foreign forces killed in July to 32, for a total of 247 so far this year.
Pakistan has accused Afghan and Nato forces of not doing enough to stop the rising number of cross-border attacks, which it says have killed dozens of members of its security forces.
However, there has been little sympathy from the US and Afghan governments, which have long complained Pakistan gives sanctuary to militants fighting in Afghanistan crossing the border in the opposite direction.
Nato later said a person wearing an Afghan national security force uniform turned his weapon against civilian contractors working with the coalition, killing three, in western Afghanistan.
The gunman was killed during the incident, which is still being investigated.