A 2.5-magnitude earthquake has been detected in North Korea near where the country recently conducted a nuclear test, Seoul's weather agency said.

The tremor occurred at 7.45am on Saturday in Kilju, North Hamgyeong Province, around 2.7 kilometres away from the Punggye-ri nuclear site, according to the Korea Meteorological Administration (KMA).

Kim Jong-Un's regime conducted its sixth and most powerful nuclear test at the site on 3 September, damaging geological structures in the area, the agency said. Four tremors have been detected there since.

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"The quake is a natural one and it is believed to have occurred in the aftermath of the sixth nuclear test," the KMA said.

The September atomic explosion triggered an artificial 6.3-magnitude earthquake at the test site, monitors at the time said. It was almost 10 times more powerful than the 10-kiloton test carried out by the North last year, according to South Korean experts.

North Korean monitoring group 38 North said the tremors could be an indication of "Tired Mountain Syndrome" — a condition where rock becomes increasingly permeable following a below-ground nuclear blast.

Reports have speculated the nuclear test site will have to close because of the tremors, but 38 North said "complete abandonment of the test site as a whole remains unlikely".

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The isolationist state recently tested a new intercontinental ballistic missile that, it claimed, could reach anywhere on the US mainland.

Experts said the Hwasong-15 appeared capable of transporting a nuclear warhead, although it is unclear whether the isolated state is yet capable of making a weapon small enough to be fitted to the missile.

North Korea announces intercontinental missile launch Show all 13 1 /13 North Korea announces intercontinental missile launch North Korea announces intercontinental missile launch Pyongyang residents react after the news of the successful launch of the new intercontinental ballistic missile AFP/Getty Images North Korea announces intercontinental missile launch North Korea's leader Kim Jong Un signing an order to test-fire the newly developed inter-continental ballistic missile KRT via AP Video North Korea announces intercontinental missile launch A news broadcast displays Kim Jong Un's signed document AP North Korea announces intercontinental missile launch People cheer as they watch the news broadcast announcing Kim Jong Un's order to test-fire the new inter-continental ballistic missile AFP/Getty Images North Korea announces intercontinental missile launch Residents react after the document signing AP North Korea announces intercontinental missile launch Pyongyang residents celebrate Kim Jong Un's announcement AFP/Getty North Korea announces intercontinental missile launch Cheering Pyongyang residents react AP North Korea announces intercontinental missile launch To counter North Korea's missile test, South Korea fired missiles into the East Sea The Defence Ministry/Yonhap via REUTERS North Korea announces intercontinental missile launch The Hyunmu-2 missiles firing during the drill South Korean Defense Ministry vi North Korea announces intercontinental missile launch The exercise was carried out in an attempt to counter Kim Jong Un's order South Korea Defense Ministry via AP North Korea announces intercontinental missile launch The South Korean army continue to carry out military exercises AP North Korea announces intercontinental missile launch Where K-9 self-propelled howitzers were taking part in a drill Rex Features North Korea announces intercontinental missile launch US soldiers are also present in the border city of Paju AFP/Getty Images

At the end of November the US unveiled fresh sanctions against the North, which it said were designed to stop its funding of nuclear and ballistic missile programmes.

Donald Trump has also redesignated North Korea as a state sponsor of terrorism.

On Friday the US state of Hawaii tested a nuclear attack warning siren for the first time since the Cold War. Some experts believe a North Korean missile could take just 20 minutes to reach the state.