North Korea could be almost ready to carry out its threat to conduct a nuclear test, a US research institute said, pointing to recent satellite photos.

North Korea is digging a new underground tunnel in what appears to be preparation for a third nuclear test, according to South Korea.

The US and South Korea have pinpointed 11 underground sites in North Korea where a third nuclear test could be conducted, a newspaper reported today ahead of a summit between the two allies on the communist regime’s growing atomic threat.

South Korea has sent a delegation to observe a US-led anti-proliferation exercise, the Foreign Ministry said today, despite Seoul’s reluctance to fully participate in an initiative that could antagonise its northern neighbour.