About 16,000 residents in Brest were evacuated yesterday to make way for a major operation to rid the northern French city of unexploded ordnance dating from World War II.

Sirens wailed as some 400 police officers and firefighters fanned out to ensure everyone had left the designated security zone in downtown Brest before mine-clearing experts were sent in to begin work.

The evacuation was decided last month and many residents had decided to leave their homes on Saturday and stay with friends during the security sweep.

City officials had set up temporary shelters for evacuees left homeless during the operation from 7 a.m. (0500 GMT) to 10 p.m. (2000 GMT).

An important German naval base during World War II, Brest was heavily bombed by Allied forces in August and September 1944.

Experts estimate that some 10 per cent of the 30,000 tonnes of explosives that rained on the city during the allied campaign still pose a threat.

Using metal detectors, mine-clearing units have found 83 shells and 15 other potentially dangerous objects that had to be removed yesterday.

A three-man team was also to scan a former naval base facility near the city centre for mines and other unexploded ordnance that will be destroyed during a second operation planned for August 15.

Brest, on France's western tip, has staged several mine-clearing operations. In March, 3,000 residents were evacuated from an area near the port to allow units to defuse a 250-kilogram US bomb.