Thousands of Pyongyang residents gathered in the capital to laud  Kim Jong-Un's denunciation of US President Donald Trump. Pic/AFP
Thousands of Pyongyang residents gathered in the capital to laud  Kim Jong-Un's denunciation of US President Donald Trump. Pic/AFP

A shallow 3.5-magnitude earthquake hit North Korea near the country's nuclear test site yesterday, US seismologists said, in what China's seismic service said was a "suspected explosion", but Seoul deemed a "natural earthquake".

The earthquake came after days of increasingly bellicose rhetoric between US President Donald Trump and North Korean leader Kim Jong-Un's regime over Pyongyang's nuclear ambitions raised international alarm. The US Geological Survey (USGS) said the quake struck around 20-km away from the North's nuclear test site, where earlier this month it detonated its sixth and largest device, which it claimed to be a hydrogen bomb capable of being launched onto a missile.

"We cannot conclusively confirm at this time the nature [natural or human-made] of the event," USGS said in a statement.

Regional experts differed on their analysis of the tremor, with Beijing's China Earthquake Network Centre service calling it a "suspected explosion", while Seoul's Korea Meteorological Agency judged it a "natural quake".

However, China's Earthquake Administration said later that the quake was not a nuclear explosion and had the characteristics of a natural tremor.