A massive Second World War bomb, which triggered the evacuation of about half of the 107,000 residents of Norwich's twin German city Koblenz, was successfully defused yesterday.

It was one of Germany's biggest bomb-related evacuations since the war ended, with some 2,500 police officers, firefighters and paramedics on duty across the city to secure the operation.

Experts successfully defused the British 1.8 ton bomb and a 275-pound US bomb that had been discovered last month after the Rhine river's water level fell significantly due to a prolonged lack of rain, said Heiko Breitbarth, a spokesman for Koblenz's firefighters.

Some 45,000 residents living within a radius of about 1.2 miles from the bomb site had to leave their houses early yesterday before the evacuation order was lifted in the evening, the city said on its website. Among those ordered to evacuate were seven nursing homes, two hospitals and a prison with some 200 inmates.

The British bomb could have caused massive damage if it had exploded.

'I did my job, that was all,' lead defusing expert Horst Lenz told local daily Rhein Zeitung.

Finding unexploded bombs dropped by the allies over Germany during the war is common over 65 years after the war's end.