The second bomb was found after a 500kg bomb was defused on Sunday at the same construction site in Wanchai. Photo: Facebook, HK Police

Police bomb disposal experts safely defused a second wartime bomb on Thursday found at the same construction site on Hong Kong Island where another big unexploded device was unearthed days earlier.

It took 24 hours to defuse the 450kg bomb at the site on Convention Avenue in Wanchai, where work is being done on the Sha Tin to Central MTR Line.

Police officer Alick Mcwhirter, from the Explosive Ordnance Disposal Bureau, said the second operation was particularly difficult as the bomb was in a dangerous condition and its location made it hard to get equipment near it, according to a briefing on Facebook.

Workers at the site found the second bomb at 11am on Wednesday – just 10 meters from where the first bomb was found on Saturday.

The rainy weather on Wednesday also made the experts difficult to secure the bomb’s location and stabilize it.

Officers began “burning” the explosive inside the bomb at 8am on Thursday and finished that task at around 11am. Black smoke was seen while the air was filled with the smell of explosives during the burning.

About 5,000 people in Wanchai – office workers in commercial buildings, residents in residential buildings and visitors in hotels – had to move out.

Roads were closed overnight but reopened around noon on Thursday.

The bomb, like the one unearthed on Saturday, was 145 centimeters long and 45cm in diameter. It was believed to be a US-made ANM-65 device dropped between 1941 and 1945 during the Japanese occupation of Hong Kong.

ReadPolice take 26 hours to defuse WWII bomb found in Wan Chai

Asia Times Financial is now live. Linking accurate news, insightful analysis and local knowledge with the ATF China Bond 50 Index, the world's first benchmark cross sector Chinese Bond Indices. Read ATF now.