North Korea has warned Japan that any sanctions against the communist state would be regarded as a declaration of war. Opinion polls show about two-thirds of the Japanese public supporting economic sanctions over the issue of Japanese kidnapped by North Korea during the Cold War.

North Korea's Central News Agency quoted an official as saying the country will hit Japan with an "effective physical response" if Tokyo imposes sanctions. The official on Wednesday also threatened to end Pyongyang's participation in multi-lateral negotiations about its nuclear weapons programs.

But Pyongyang is already holding up those talks. Frank Jannuzi, Asia specialist for the U.S. Senate Foreign Relations Committee, says the threat of sanctions could help force the North back to the table.

"Pyongyang, left to its own devices, will choose not to choose," said Mr. Jannuzi. "And therefore, in attempting to create a pressure point for a choice by the Pyongyang government, I think there is a role for sanctions."

But Mr. Jannuzi says sanctions would have to be backed by China and South Korea to be effective.

The South Korean government on Wednesday expressed its opposition to sanctions. Foreign Minister Ban

Ki-moon told reporters that such a move would complicate efforts to resolve the nuclear standoff. Mr. Moon said the abduction issue should be resolved through serious bilateral talks between Pyongyang and Tokyo.

Japan and North Korea have no diplomatic relations. Japan says a pre-requisite to normalized ties is the resolution of the abduction issue.

North Korea admits to abducting 13 Japanese during the Cold War so they could train North Korean spies. Five abductees were sent back to Japan in 2002, but Pyongyang says the other eight have died. The families of the eight believe they are still being held alive by North Korea.

Earlier this month, Japan said DNA tests revealed that human remains turned over to Japan, which Pyongyang said were those of two of the dead, were actually those of other people. The Japanese public was furious, but North Korea on Wednesday accused Japan of cooking up the test results for political purposes.

Japanese Prime Minister Junichiro Koizumi calls North Korea's attitude toward the abduction issue "abominable."

But Mr. Koizumi has yet to express support for sanctions against Pyongyang, saying he wants to promote negotiations and make any judgment on sanctions at an appropriate time.