Berlin  - Senior NATO officers responsible for fighting the Taliban in Afghanistan have rejected an order also to fight non- Taliban drug gangs, according to news reports which were confirmed by German military sources on Thursday.

A US general in Kabul and a German general overseeing NATO's International Security Assistance Force (ISAF) from Europe have told the NATO supreme commander, General John Craddock of the United States, that his order is illegal.

Craddock had asked NATO troops to use lethal force against opium traders without requiring intelligence data to prove they were passing money to the Islamic fundamentalist Taliban or in rebellion against the Kabul government.

The website of the news magazine Der Spiegel said General Egon Ramms, who heads a command overseeing ISAF from Brunssum, the Netherlands, and General David McKiernan, who runs ISAF on the ground, told Craddock the order was in breach of their rules of engagement and the laws of armed conflict.

Their stance largely aligns with Berlin's concerns about "mission creep," a term for ISAF taking on new tasks that put it at odds with ordinary Afghans whose goodwill is essential to armed peacekeepers.

German military sources in Berlin confirmed there was a dispute under way and German opposition parties demanded an explanation.

Ramms is a four-star general responsible for the 55,000 ISAF personnel.

In Brussels, a spokesman for Craddock defended the order, saying it was not illegal and was based on a decision last October by NATO defence ministers to attack "drug facilities and persons supporting rebellion."

Thomas Raabe, German Defence Ministry spokesman, told Deutsche Presse-Agentur dpa that German forces provided logistics and intelligence support to Afghan security forces fighting drug gangs.

However German soldiers did not participate in lethal operations which might target drug dealers who were not demonstrably rebels. dpa