The threat, made by a North Korean foreign ministry spokesman on Thursday in an interview with state media in Pyongyang, was "deplorable", a Japanese foreign ministry official said.

"The Japanese government renews its strong demand that North Korea avoid any action that may aggravate the situation," the foreign ministry spokeswoman said.

"At the same time, it will continue cooperating closely with the United States, South Korea and other countries concerned in seeking a peaceful, diplomatic solution to the issue," she said.

She added that Tokyo would "make diplomatic efforts to yield a responsible and forward-looking response from North Korea toward the settlement of the issue."

At a six-nation meeting on the Korean nuclear crisis in Beijing in late August, all sides agreed on a six-point consensus, according to hosts China.

Among other things, the countries -- North and South Korea, China, Japan, Russia and the United States -- committed themselves to resolve the nuclear issue through peaceful means and dialogue.

They also agreed that "in the process of negotiations any action that may aggravate the situation should be avoided."

There has been no date set for a second round of six-way talks while North Korea has said Japan should be excluded from the forum for dwelling too much on what it regards as the unresolved abduction of Japanese nationals by North Korean agents in the 1970s and 1980s.

WAR.WIRE