Brussels  - NATO soldiers will only be allowed to target Afghan drug traffickers if they can be shown to be providing "material support" to the Taliban insurgency, the alliance's spokesman said Wednesday.

James Appathurai said NATO Supreme Commander General John Craddock had agreed to clarify the rules of engagement following reports that senior officers on the ground were refusing to fight drug gangs which were not proven to have links with the Taliban.

According to the revised rules, NATO's 55,000-strong International Security Assistance Force (ISAF) will only be able to target traffickers and their laboratories "where they provide material support to the insurgency," Appathurai said.

Last week, leaks to the German media showed that ISAF commanders were concerned that killing traffickers without being certain that they were helping the insurgency would breach international law.

Such concerns have found plenty of sympathy in Berlin, which fears that ISAF may be taking on new tasks that put it at odds with ordinary Afghans, whose goodwill is essential to armed peacekeepers.

"ISAF is fully aware of the importance of taking every step possible to diminish civilian casualties and to take into account the very real and legitimate sensitivities of the Afghan people," Appathurai said.

"Everything that will be done by ISAF will be done in full compliance with international law," the spokesman said.

NATO defence ministers agreed in October to target drugs traffickers and opium laboratories in Afghanistan as part of the alliance's efforts to undermine the Taliban insurgency.

Ministers from Germany, Spain and Italy argued in Budapest that the fight against drugs should be left to the Afghan police. (dpa)