SEOUL - A 2.1-magnitude earthquake in North Korea's mining town of Pyonggang at around noon on Thursday (March 7) is believed to have been man-made, with the Korean Meteorological Administration (KMA) indicating that the tremor was the result of an explosion.

"The epicentre is measured to be near the land surface," a KMA official said.

The quake comes two days after South Korea's spy agency said that North Korea was rebuilding part of a dismantled long-range missile test site in Sohae, reported The Korea Times.

It comes shortly after a summit between United States President Donald Trump and North Korean leader Kim Jong Un ended without an agreement over differences on the extent of denuclearisation by Pyongyang.

The latest incident threatens to cast a cloud over future meetings, coming in the wake of South Korean spy chief Suh Hoon's warning that cargo vehicles were spotted recently moving around a North Korean intercontinental ballistic missile factory, the JoongAng Ilbo reported.

Mr Suh has also said that North Korea continued to operate a uranium enrichment facility at the main Yongbyon nuclear complex after a first summit between Mr Trump and Mr Kim in June last year.

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Days after the Trump-Kim summit failed, construction work was spied by satellites at North Korea's Sohae Satellite Launching Station, The Independent reported.