Nato took over eastern Afghanistan from US-led forces yesterday, assuming control of 12,000 US troops and expanding their security mission to the entire country.

The commander of the Nato-led force, British Gen David Richards, who was promoted to a four-star general yesterday, called the move "historic" in a ceremony also attended by President Hamid Karzai and US Lt Gen Karl Eikenberry.

The hand-over "illustrates the enduring commitment of Nato and its international partners to the future of this great country," said Richards.

With about 12,000 troops, the US is the biggest contributor to the 31,000-strong Nato force. Britain has 5,200 troops and Germany has 2,750 troops in Afghanistan.

"A key point to remember in this transition is that the United States maintains its full commitment to Afghanistan," Eikenberry said. "As a Nato member, the United States will remain by far the single-largest contributor of troops and military capability."

Eikenberry said that unify-ing the military command enhances Western troops' effectiveness and allows greater flexibility in the use of assets.

An additional 8,000 US troops - those tracking al Qaida terrorists, helping train Afghan security forces and doing reconstruction work -will function outside Nato control.

The command consolidation confines direct US control to a single chief enclave: the sprawling American base at Bagram.