The United Nations secretary general has again spoken out against the "appalling" toll of civilians killed and hurt as NATO forces battle insurgents in Afghanistan.

Speaking to reporters on Monday, Ban Ki-moon said he remonstrated with North Atlantic Treaty Organization officials during a visit to Afghanistan in June and at a conference in Rome in early July.

UN Secretary General Ban Ki-moon says NATO forces must stop killing civilian bystanders while fighting the Taliban.
(Ahn Young-joon/Associated Press)

"One of the important areas which I addressed is the increasing number of civilian casualties in Afghanistan," he said.

NATO civilian and military chiefs "assured me that they will take necessary precautionary measures to avoid any further civilian casualties," he said.

Ban said he understands the problem faced by NATO forces.

"I know that it is extremely difficult, because insurgents and Talibans are trying to hide behind the general population, so it makes it very difficult in the course of military operations to differentiate who are innocent citizens and who are insurgents.

"But I emphasized strongly, publicly and privately, that they should take necessary measures."

Extremists in 'different moral category'

Canadian and other NATO ground troops have mistakenly shot a number of Afghan civilians, but errant air strikes and artillery fire have caused the biggest groups of civilian deaths.

According to an Associated Press tally in June, NATO and U.S.-led forces had killed at least 203 civilians since the beginning of the year, while militant attacks killed 178.

At the Rome conference July 3, NATO Secretary General Jaap de Hoop Scheffer said the alliance would do everything in its power to avoid civilian casualties and that deaths of innocent people would be investigated.

He stressed, however, that Taliban and other extremists were in a "different moral category" from coalition soldiers who inadvertently cause civilian casualties.

"Our opponents mingle and mix with innocent civilians," he said.

"We do not intentionally kill; they behead people, they burn schools, they kill women and children."

"That said, NATO will do and has to do everything in its ability to prevent civilian casualties. For NATO, every single civilian life lost in Afghanistan is one too many."