A large metal sphere that washed up on a shore in Japan has perplexed locals and set off a flurry of speculation.

Authorities can't say what it is yet - not even the police or bomb squad sent to investigate.

But what is known is that it's hollow - and not a threat. Many suspect it to be a type of buoy.

The find in coastal city Hamamatsu has been variously dubbed "Godzilla egg", "mooring buoy" and "from outer space" by fascinated locals.

Japanese broadcaster NHK showed footage of two officials on Enshuhama Beach looking at the rusty, metal sphere that appeared about 1.5m (4.9ft) wide.

It had been found by a local who alerted police after noticing the unusual object on the shore.

Authorities cordoned off the area and conducted X-ray exams which did not reveal much more - other than confirming the object was safe.

A runner on the beach told local media he was surprised by the commotion, as the ball had been there for some time. "I tried to push it but it wouldn't budge," NHK reported him saying.

Local authorities have said the object will be removed soon.

This kind of find might not normally raise suspicion - but it comes amid general nervousness over unidentified objects since the US shot down a suspected Chinese spy balloon earlier this month.

Japan separately expressed concern to China on Wednesday about suspected surveillance balloons spotted over its skies at least three times since 2019 - an allegation it first made last week. Beijing denies claims of espionage.

The two countries' defence ministers met on Wednesday, in the first senior bilateral security dialogue in four years. Both sides agreed to work toward launching a communications hotline this spring. (BBC)

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