"NATO will take over everything involving organization, implementation, planning and command" of the ISAF mission, which has patrolled Kabul and its environs since its creation in December 2001 following the fall of the Taliban militia, said a diplomat.

ISAF currently comprises some 4,600 troops from 29 countries, including around 2,500 German military and 600 Dutch soldiers, and provides assistance to Afghan authorities in securing Kabul.

Germany and the Netherlands took over joint control of ISAF from Turkey in February. Berlin has urged NATO to take over the leadership role at the end of the current mandate in August, but other countries including France and Belgium have expressed reservations.

Formally, ISAF will not become a NATO mission, the source said, addding that it would be a "successor mission". "Neither the name nor the mandate of this force will change," he said.

The decision was taken by the Alliance's ruling North Atlantic Council (NAC) at the NATO's Brussels headquarters Wednesday morning.

NATO is currently undergoing a radical transformation, from a Cold War-era bloc whose actions have been geographically limited to a post-September 11 force focussed on threats worldwide.

At a landmark summit in Prague last year it agreed to expand to take in seven ex-communist countries, while also approving the creation of a rapid Response Force (NRF) ready for combat missions anywhere around the globe.

Alliance ambassadors asked their military experts on April 2 to study how the alliance could "maximize" the Alliance's role in Afghanistan.

NATO's top military commander in Europe, General James L. Jones, said last month that the alliance was ready to play a leading role, if called upon.

"I am quite sure that NATO assets could be used, and could be used effectively," he said after talks with German Defence Minister Peter Struck.

SPACE.WIRE