THOUSANDS OF PEOPLE were evacuated from their homes in Hong Kong overnight so experts could defuse a large US-made bomb left over from the Second World War that was discovered at a building site.

Police said the bomb was 1.5 metres in length and weighed about 450kg.

It was discovered by construction workers in Quarry Bay, a bustling residential and business district on the west side of Hong Kong island.

“We have confirmed this object to be a bomb dating back to World War II,” said Andy Chan Tin-Chu, a police official, speaking to reporters ahead of the operation.

He said that because of “the exceptionally high risks associated with its disposal” approximately 1,900 households involving 6,000 individuals were “urged to evacuate swiftly”.

The operation to deactivate the bomb began late on Friday and lasted until around 11:30am on Saturday. No one was injured in the operation.

Bombs left over from the Second World War are discovered from time to time in Hong Kong.

The city was occupied by Japanese forces during the war, when it became a base for the Japanese military and shipping. The United States, along with other Allied forces, targeted Hong Kong in air raids to disrupt Japanese supply lines and infrastructure.