The new force, called EUFOR, steps into the shoes of Nato 's departing Stabilisation Force (SFOR) on Thursday.

But 9 years after the end of the war which cost 200,000 lives, hostilities have cooled and its 7,000 soldiers are unlikely to face danger.

The operation is expected to last a maximum of 3 years.

Eighty percent of soldiers in the new force are there already under SFOR command. They simply swapped insignia on their caps, uniforms and vehicles to EUFOR.

The handover was marked by Nato, EU and Bosnian officials at a ceremony at Camp Butmir just outside Sarajevo.

A British military brass band in red uniforms and fur hats lined up with a Bosnian honour guard and SFOR soldiers from 28 countries as the EU's bright-blue flag was raised.

"This is a truly historic occasion. This is a watershed in Bosnia and Herzegovina's development," said Nato Secretary General Jaap de Hoop Scheffer.

Scheffer said he was proud of Nato 's accomplishments in Bosnia and stressed that the alliance was staying on to assist in the hunt for war crimes fugitives.

EUFOR's troops come from 22 EU member states and 11 other countries, including Canada, Chile and Morocco.

EU foreign policy chief Javier Solana, a former Nato secretary general, said its deployment proved the EU's commitment to helping Bosnia achieve its goals of democracy and stabilisation, and its future in Europe.

British General David Leakey, who will head the EU's biggest military operation so far, says EUFOR will continue the SFOR mandate to provide "safe and secure" environment and assist in the fight against organised crime.

The EU hopes to trim the force along the way if the situation on the ground permits, and to wind it up in three-years.