Seoul (AsiaNews/Agencies) – North Korea is preparing to test nuclear weapons according to official sources in the United States who base their claims on satellite photos taken over the north-eastern part of the country.

The images show preparations to be almost complete, including the digging of a tunnel that resembles the one used in Pakistan for nuclear tests in 1998, as well as the construction of a reviewing stand, presumably for dignitaries.

This would be the first nuclear test after the Communist nation announced back in February that it possessed nuclear weapons and that it was "suspending" its participation to talks designed to limit nuclear weapons because the "conditions were not yet mature".

Official White House sources stated that it was impossible to gauge the intentions of North Korean leader Kim Jong-li.

Experts said however there were no signs of the electronic equipment often used to monitor the size and success of a nuclear test, but the US is treating the issue with extreme caution and have fully informed Japan and South Korea.

Tokyo and Seoul slammed the launch last week of a North Korean missile into the sea at 100 km from the coastline. That weapon did not appear to be nuclear warhead compatible.

The head of South Korean security, Kwon Jin-ho, stated that "no unusual activity has been reported" and a "nuclear test is unlikely in the immediate future".