In a statement released by the official Korean Central News Agency (KCNA), North Korea said it no longer felt bound by the Korean War armistice and that anyone who provoked it would "face unimaginable merciless punishment."

The statement added that the regime of Kim Jong Il could no longer guarantee the safety of US and South Korean ships off its western coast.

The hard-line announcement came in response to Seoul’s decision to join the Proliferation Security Initiative (PSI), which provides for the searching of ships thought to be carrying any part of weapons of mass destruction.

South Korea became a full member of the PSI on Tuesday after North Korea conducted a second internationally condemned nuclear test Monday, considerably more powerful than its first test almost three years ago, and also fired several short-range missiles.

But the North made it clear in its statement that it would not tolerate the stopping and searching of its ships. Anyone attempting to do so, it said, would face an "immediate and strong military strike."

International response

The five permanent members of the United Nations Security Council plus South Korea and Japan met behind closed doors on Tuesday night for talks on a possible new resolution following this latest nuclear test.

The Russian ambassador, Vitaly Churkin, who currently holds the rotating council presidency, said Russia planned to support a tough resolution. He said the group was looking at different points of view and a variety of suggestions, but that it was too early to talk about them.

Speaking after the meeting, US ambassador to the UN Susan Rice said "I think we are off to a good start,“ but added that the meeting was just the first step.

tw/dpa/AFP

Editor: Robert Mudge