World War II bomb explodes at a Japanese airport, causing a large crater on runway

An unexploded US bomb from World War II that had been buried at a Japanese airport has exploded, causing a large crater in a runway and the cancellation of more than 80 flights but no injuries, Japanese officials said.

Land and Transport Ministry officials said there were no aircraft nearby when the bomb exploded at Miyazaki Airport in south-western Japan on Wednesday.

Officials said an investigation by the Self-Defence Forces and police confirmed that the explosion was caused by a 230kg US bomb and there was no further danger. They were determining what caused its sudden detonation.

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A video recorded by a nearby aviation school showed the blast spewing pieces of asphalt into the air like a fountain.

Videos broadcast on Japanese television showed a crater in the taxiway reportedly about 7m in diameter and 1m deep.

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Miyazaki Airport was built in 1943 as a former Imperial Japanese Navy flight training field from which some kamikaze pilots took off on suicide attack missions.

A number of unexploded bombs dropped by the US military during World War II have been unearthed in the area, Defence Ministry officials said.

Hundreds of tonnes of unexploded bombs from the war remain buried around Japan and are sometimes dug up at construction sites.