200 feared buried as tunnel collapses after N Korea conducts nuclear test

More than 200 people are feared to have died after underground tunnels at a nuclear test site that was feared to be unstable reportedly collapsed.

About 100 people were trapped inside when the unfinished tunnel at the North's Punggye-ri nuclear test site collapsed, and an additional 100 people could have been killed while trying to rescue those trapped as a second collapse occurred, Japan's TV Asahi reported.

Experts have said a series of tremors and landslides near the nuclear test base probably mean the country's sixth and largest blast on 3 September has destabilised the region, and the Punggye-ri nuclear site may not be used for much longer to test nuclear weapons.

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

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.

The series of quakes prompted experts to suspect the test of the hydrogen bomb may have damaged the mountainous location where all of North Korea's six nuclear tests were conducted.

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.

This second tunnel could have collapsed after the test of the hydrogen bomb, experts said.

OneIndia News (with agency inputs)