NATO forces in eastern Afghanistan say four Afghan civilians were killed and two were wounded in militant attacks on Saturday.

NATO issued a statement Sunday saying insurgents fired mortars and assault weapons at the Waze Zadran district center and a nearby security outpost in Paktia province, killing one Afghan.  It said Afghan and NATO troops responded to the attack while NATO provided medical assistance to the wounded.

Also in Paktia province, the statement says militants attacked Afghan workers who were constructing the Khost-Gardez road in Shawak district, killing three Afghan security guards at the site.
News of the violence comes as the United Nations sounds another warning about the cost of civilian casualties in Afghanistan.

U.N. Special Representative to Afghanistan Kai Eide says the world "cannot afford" mistakes that lead to the killing of innocent bystanders because they overshadow efforts to help the country.

Eide spoke to NATO defense ministers meeting in Brussels late Friday, but his comments were not made public until Saturday.

Earlier Friday, U.S. Defense Secretary Robert Gates warned every civilian casualty "is a defeat" and "a setback."

The warnings come as Afghanistan is confronting another wave of violence.