Tremor shakes North Korea

A shallow tremor struck North Korea on Sunday, prompting fears that Pyongyang may have conducted a nuclear test.

The website of the US Geological Survey said the tremor of 6.3 magnitude had a depth of 23 kilometres, an alert that came after claims by Pyongyang that the North has developed a more advanced nuclear weapon that has "great destructive power".

"Possible explosion, located near the site where North Korea has detonated nuclear explosions in the past," said the USGS.

"If this event was an explosion, the USGS National Earthquake Information Center cannot determine its type, whether nuclear or any other possible type."

The USGS had earlier reported a 5.2 magnitude and depth of zero kilometres.

Previous recent tremors in North Korea have been caused by nuclear tests.

The South Korean military confirmed that an artificial quake took place near North Korea's nuclear test site and has put its nuclear crisis response team into operation, according to the Yonhap news agency.

There were slight variations of the earthquake's measures.

South Korea's Joint Chiefs of Staff reported a magnitude 5.6 quake.

China's Earthquake Administration said it detected a 6.3 magnitude earthquake with a depth of zero kilometres in North Korea that was a "suspected explosion".

The administration said in a statement on its website that the quake was recorded around 11:30am (03:30 GMT).

Al Jazeera's Wayne Hay, reporting from Seoul, said: "The size of this earthquake does vary upon which organisation is reporting it.

"The location of the earthquake was in the northeast of the country and there had been reports in the past few weeks, citing South Korean intelligence, there was movement at that site. So they were suspecting that maybe [North Korea was] preparing for another nuclear test.

"There was a lot of expectation they would conduct their nuclear test on September 9, the date they did it last year, to mark Foundation Day, the founding day of [North Korea]."