An unexploded US bomb dating from the Second World War that had been buried at a Japanese airport has exploded, causing a large crater in a taxiway and the cancellation of more than 80 flights.

No-one was injured in the incident at Miyazaki Airport in south-western Japan, officials said.

Land and transport ministry officials said there were no aircraft nearby when the bomb exploded.

Officials said an investigation by the Self-Defence Forces and police confirmed that the explosion was caused by a 500lb US bomb, and there was no further danger. They were determining what caused its sudden detonation.

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

Videos broadcast on Japanese television showed a crater in the taxiway reportedly about 21ft in diameter and 3ft deep.

Chief cabinet secretary Yoshimasa Hayashi said more than 80 flights had been cancelled at the airport, which hopes to resume operations on Thursday morning.

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 the Second World War 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.