TOKYO - More than 200 people are feared to have died when a tunnel caved in at North Korea’s nuclear test site after its latest detonation, a Japanese news report said Tuesday.

A tunnel collapsed at Punggye-ri in early September, days after North Korea conducted its sixth and largest underground nuclear test on September 3, TV Asahi said, quoting unnamed North Korean sources.

Some 100 workers were involved in an initial collapse. Another cave-in occurred during rescue operations, leaving at least 200 people feared dead in total, the Japanese broadcaster said. The accident was triggered by the test, TV Asahi added.

Experts have warned that the underground tests could cause the mountain to collapse and leak radiation into the atmosphere near China’s border.

The latest test - the sixth at the site since 2006 - triggered landslides in the detonation area and beyond, according to satellite pictures taken the day after.

The images published by the 38 North website showed changes in the surface at Punggye-ri where the ground had been lifted into the air by the tremors. Small landslides followed the course of stream beds.

The blast caused a 6.3-magnitude earthquake, according to the US Geological Survey, followed a few minutes later by another with a magnitude of 4.1.

Japan assessed the yield from the test of what the North said was a hydrogen bomb at 120 kilotons, eight times the size of Hiroshima in 1945.

It is very unusual for North Korea to acknowledge any major accident, especially anything that involves its nuclear programme.

Lee Eugene, a spokeswoman at South Korea’s unification ministry, said: “We are aware of the report but do not know anything about it.”

The report came ahead of US President Donald Trump’s first presidential visit to South Korea next week amid an escalating war of words between him and North Korean leader Kim Jong-Un.

The reclusive country has made significant strides in its atomic and missile technology under Kim, who took power after the death of his father and longtime ruler Kim Jong-Il in 2011. Since then he has overseen four of the country’s six nuclear tests and hailed atomic weapons as a “treasured sword” to protect the nation from invasion by the United States.

N Korea denies involvement in

WannaCry cyberattack

North Korea has slammed Britain for accusing it of being behind a global ransomware attack that hit the National Health Service, calling the allegation a “wicked attempt” to further tighten international sanctions against Pyongyang. A third of Britain’s public hospitals were affected by the WannaCry worm in May, according to a government report.

Up to 300,000 computers in 150 countries were hit by WannaCry, which seized systems and demanded payment in Bitcoin to return control to users.

Some researchers have pointed the finger at Pyongyang, saying that the code used was similar to past hacks blamed on Kim Jong-Un’s regime.

British Home Office minister Ben Wallace told the BBC last week that London was “as sure as possible” that North Korea was responsible.

But a spokesman for the North’s Korea-Europe Association denied the accusations and warned Britain against “groundless speculation”.

Trump won’t go to DMZ

during S.Korea visit

US President Donald Trump will not be going to the De-Militarized Zone dividing the Korean peninsula when he visits South Korea next week, a senior administration official said Tuesday.

The decision to skip the DMZ at a time of high tensions with nuclear-armed North Korea was attributed to time constraints. “The president is not going to visit the DMZ, there is not enough time in the schedule,” the official said.

Trump, who departs Friday on a five-nation Asian tour with world attention on North Korea’s nuclear and missile programs, will instead visit Camp Humphreys, which is south of Seoul and away from the DMZ, the official said.

The DMZ, a razor’s edge separating North and South Korean forces, is a common stop for visiting presidents and other high-level US officials wanting to see one of the world’s most dangerous flashpoints.

But the senior administration official downplayed the decision not to go.

“We just had Secretary Mattis there last week, we had Vice President Pence there earlier this year,” the official said, referring to Pentagon chief Jim Mattis and Trump’s number two, Mike Pence.

“It’s becoming a little bit of a cliche, frankly.”