0337 GMT: An “artificial earthquake of 5.1 magnitude” has been detected in Kilju county, where the Punggye-ri test site is located, according to Yonhap news agency.
The US Geological Survey measured it as a 4.9-magnitude quake at a very shallow depth of just one kilometre (0.6 miles).
Reports say that South Korea has detected an “artificial earthquake” at North Korea’s nuclear test site, suggesting Pyongyang had gone ahead with a threatened atomic test.
WELCOME to AFP’s Live Report on the suspected nuclear test in North Korea.
Just hours before the suspected test, North Korea’s ruling party called for the staging of a “high-intensity” action and further long-range rocket launches.
Recent satellite imagery analysis of the North’s remote nuclear test site, as well as US and South Korean intelligence reports, all concluded that the North had completed all necessary test preparations.
Pyongyang has said any test would be a direct response to the UN Security Council’s adoption of a US-proposed resolution that condemned the North’s rocket launch in December and expanded existing sanctions.
North Korea insists the rocket launch was a scientific mission aimed at putting a satellite into an orbit.
But the United States and many other countries viewed it as a disguised ballistic missile test, banned under UN resolutions triggered by Pyongyang’s previous nuclear tests in 2006 and 2009.