NATO says two non-Afghan civilians and 14 insurgents were killed in eastern Afghanistan on Friday after insurgents attacked a coalition base.

Officials say a suicide car bomber and other insurgents raided the facility outside of the city of Khost.

An ISAF regional command spokesman tells VOA the insurgents were killed in clashes with coalition forces who eventually repelled the attackers.

The spokesman says it is unclear how the two civilians died. He said one was from the United States but did not disclose the nationality of the second civilian.

The Taliban has claimed responsibility for the attack.

The ongoing violence in Afghanistan has raised concerns about the ability of Afghan forces to handle security after NATO pulls combat troops out of the country by the end of 2014.

On Thursday, the United Nations Assistance Mission in Afghanistan said civilian casualties from the Afghan conflict remain at “unacceptably high levels.”

UNAMA said it documented more than 3,000 conflict-related civilian deaths last year, three-quarters linked to violence by anti-government forces.