China's earthquake administration said on Saturday it had detected a magnitude 3.4 earthquake in North Korea that was a "suspected explosion", but it was still unclear whether the nation had actually conducted a new nuclear test.
Amid a growing war of words between Pyongyang and Washington, Chinese officials said in a statement on its website that the quake, which occurred around 0830 GMT, was recorded a depth of zero kilometres.
Previous quakes from North Korea have indicated nuclear tests by the reclusive state, the most recent earlier this month. The quake was centred near North Korea's nuclear test site.
The war of words between President Donald Trump and the leader of North Korea escalated Friday, with Trump saying North Korean leader Kim Jong Un "will be tested like never before."
The president's comment came in response to Kim excoriating Trump for his speech at the United Nations earlier this week, which heightened fears of an armed conflict.
'Unlikely man-made'
South Korea's weather agency said it was analyzing the nature of the quake, and its initial view was that it was a natural earthquake.
Shortly after, the nuclear proliferation watchdog CTBTO said that the seismic activity on the Korean Peninsula took place around 50 kilometers from prior tests. Lassina Zerbo, the executive secretary of the agency said there were actually two seismic activities.
In a tweet, Zerbo said that the quake is "unlikely man-made." Analysts from the agency are still investigating.
The United States Geological Survey (USGS) said that the quake occurred in a previous area of a North Korea nuclear test. But the agency said in a statement on Saturday that it "cannot conclusively confirm" whether this was a natural or human-made event.
The agency said that it was a 3.5 magnitude quake, a touch stronger than the 3.4 magnitude that Chinese authorities had discovered.
Seismic tremors often occur in North Korea after a nuclear test. Earlier this month, a 6.3 magnitude hit North Korea following a nuclear test.
--CNBC's Arjun Kharpal and Javier E. David contributed to this article.