NORTH Korea could be preparing another ballistic missile test after “brisk activity” at one of Kim Jong-un’s nuclear research facilities, according to local media.

South Korea’s spy agency is anticipating another rocket launch, insisting the crackpot state would continuously push to develop "miniaturised, diversified" warheads.

5 Dictator Kim Jong-un has reportedly tested another nuclear-tipped missile causing three aftershocks Credit: Alamy Live News

The South’s National Intelligence Service (NIS) has spotted "active movement" of vehicles at Kim’s research centre in Pyongyang - indicating the war-hungry despot is preparing another test.

The NIS also mentioned damage to the Punggye-ri nuclear site in the north-east of the country after three aftershocks following the North’s sixth and most powerful nuclear test on September 3.

Last month, a tunnel at the underground nuclear site reportedly collapsed killing up to 200 people.

The disaster happened at the remote Punggye-ri site on October 10, according to Japan’s TV Asahi.

5 The Punggye-ri test site in North Korea is carved deep into Mount Mantap, as these file images show Credit: The Sun

5 Satellite images show Mount Mantap pock-marked with craters from landslides after the last nuclear test Credit: Airbus DS / Spot Image

5 North Korea state media celebrates its missile capability

The disaster has prompted fears of a massive radioactive leak which could spark a Chernobyl or Fukushima-style disaster.

A North Korean official said the collapse happened during the construction of an underground tunnel, South Korea’s Yonhap news agency reports.

Some 100 people are said to have been trapped by the initial tunnel collapse, with a further 100 lost in a second collapse during a rescue operation, Asahi reported Tuesday.

The accident is believed to have been caused by Kim Jong-un’s sixth nuclear test which weakened the mountain, according to the report.

It was reported earlier this year that the mountain, under which the base is believed to be hidden, was at risk of collapsing and leaking radiation into the region.

Experts said that if the peak crumbles, clouds of radioactive dust and gas would blanket the region, the South China Morning Post reported.

5 North Korean leader Kim Jong-un inspects what is claimed to be a hydrogen bomb that fits in the nose cone of a missile Credit: Reuters

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