North Korea has said sanctions would be a declaration of war and handed a note of protest Thursday to the Japanese embassy in Beijing over Tokyo's accusation that Pyongyang lied about the deaths of Japanese kidnap victims.

"Economic sanctions is one possible way" to pressure North Korea, Foreign Minister Nobutaka Machimura told a news conference.

"Whether they would be triggered immediately or not I think needs careful analysis," Machimura said.

He noted that other countries engaged in stalled talks on North Korea's nuclear ambitions have urged Japan to take action that is "not so drastic."

Machimura said the nuclear talks "must go on."

"This issue is one on the agenda," he said of the kidnapping dispute.

He said the decision whether to impose sanctions was "very difficult" and that final analysis on the charred human remains was due to be complete next week.

North Korean agents kidnapped a disputed number of Japanese nationals during the Cold War to train the regime's spies in Japan's language and culture.

Japan has seen growing calls to snap economic ties to cash-strapped North Korea after DNA tests on human remains handed over to a Japanese team last month were found not to match two victims as claimed by Pyongyang.

One of the two is Megumi Yokota, who was 13 when she was abducted on her way home from school in 1977 and whose case draws deep sympathy in Japan.

"Our position is that they are still alive and should be returned," Machimura said.

North Korea said Wednesday it would hit back with an "effective physical" response and reconsider participation in the nuclear talks if Japan imposed sanctions.

Machimura dismissed the war talk.

"We have no intention of anything other than dialogue, but the dialogue cannot be meaningless," he said.

"Japan, no matter who the counterpart may be, has no desire for war," he said. "The United States still has sanctions in various ways against North Korea. Does that mean it's at war?"

But the United States, Japan's closest ally, has called for prudence on whether Tokyo should impose sanctions on the unpredictable Stalinist state, which fired a missile over Japan into the Pacific in 1998.

In turn, Pyongyang's main backer China on Thursday urged Japan and North Korea not to do anything to complicate the resumption of nuclear talks.

"We hope both sides' actions will not complicate the process of the six-party talks," said foreign ministry spokesman Liu Jianchao.

"As to Japan and North Korea's bilateral issues, we hope they can resolve this issue through dialogue," he said.

South Korean Foreign Minister Ban Ki-Moon said on Wednesday the abduction dispute should be resolved by "peaceful dialogue rather than sanctions or a blockade."

The Koreas, China, Japan, Russia and the United States have held three rounds of talks aimed at ending North Korea's nuclear program after Washington said in 2002 that Pyongyang was trying to produce highly enriched uranium for atomic weapons.

But North Korea boycotted a fourth round of talks scheduled for Beijing in September.

The Stalinist state was then widely seen as awaiting the outcome of the US presidential race, in which challenger John Kerry called for bilateral talks with Pyongyang. But no date for nuclear talks has been set since President George W. Bush's victory on November 2.