Efforts to dispose of a 500kg unexploded bomb are being hindered by residents refusing to evacuate their homes.

The World War II German bomb was found on a town centre building site in Bexleyheath, Kent, on Tuesday.

An operation by police to move more than 2,000 residents from 971 homes began on Wednesday morning. But people in 70 homes would not leave.

Wartime spirit

Major Bob Tomkins, overseeing the operation, said: "Some residents are reluctant to leave their homes.

"While it might have been quite laudable in the 1940s with the great British Bulldog spirit, I don't think it appropriate any more."

The bomb disposal team is confident that a 500-metre evacuation zone is adequate.

Containment measures will reduce the explosion which could otherwise spread shrapnel over a 2,000-metre area.

In 1940, 486 bombs were recorded as falling on Bexleyheath.

"Compared with them this is a minor problem but we need to deal with it in a safe and efficient manner," added Major Tomkins.

Leaflets were delivered to homes near the bombsite telling people what to do during Wednesday's evacuation.

Chief Inspector Pat Shiel of the Metropolitan Police said teams of officers and council officials had been working together from early morning to clear the area.

The bomb, which was discovered by workmen, is currently in a nose down position, two metres below the surface at the building site.

The disposal operation is expected to take around 10 hours, once the entire area has been cleared.

In October last year, 3,000 people were evacuated from Woodley, about 50 miles west of London, when an old bomb was found on a building site.

A total of 7,500 bombs are believed to have fallen in the area during the war.