North Korea has warned Japan that it would treat economic sanctions as a "declaration of war" and threatened to try to exclude Tokyo from six-party talks on Pyongyang's nuclear arms programs.
Calls are growing from the Japanese public and politicians for the government to impose sanctions on North Korea after Tokyo said bones Pyongyang had identified as those of Japanese it kidnapped were from other people.
"If sanctions are applied against the DPRK (North Korea) due to the moves of the ultra-right forces (in Japan), we will regard it as a declaration of war against our country and promptly react to the action by an effective physical method," a spokesman for North Korea's Foreign Ministry said.
North Korea handed over the bones at talks in Pyongyang in November, saying they were the remains of Megumi Yokota and Kaoru Matsuki, two of 13 Japanese whom Pyongyang has admitted abducting in the 1970s and 1980s to teach its spies about Japan.
Japan, which does not have diplomatic ties with North Korea, lodged a protest with Pyongyang and demanded clarification on the fate of 10 Japanese who Tokyo believes were kidnapped and are still unaccounted for.
The North Korean spokesman said it was "unimaginable" that the bones handed over by Yokota's North Korean husband were not hers.
"Let's suppose he handed the remains of other person to the Japanese side, as claimed by it, then what did he expect from doing so?" the spokesman said in a statement carried by the official Korean Central News Agency, monitored in Tokyo.
The North admitted in 2002 to kidnapping the 13 Japanese, and Japan believes another two were also abducted. Five have returned to Japan.
North Korea has repeatedly said in the past that any imposition of economic sanctions by Japan would be tantamount to a declaration of war.
A hefty majority of Japanese citizens favor economic sanctions on North Korea, media polls have shown. However, Prime Minister Junichiro Koizumi has taken a cautious stance, apparently for fear of jeopardising the six-party process.
Japan's Yomiuri newspaper said on Tuesday that 74 percent of respondents to a nationwide survey believed Japan should impose sanctions on North Korea if there was no progress on the abduction issue, up from 68 percent in September.
Koizumi said on Monday he could understand the public anger but shied away from saying Tokyo should take punitive steps against North Korea.
Hiroyuki Hosoda, Japan's top government spokesman, played down North Korea's reaction.
"We can't see the value of making such comments," Hosoda told reporters.
Shinzo Abe, who heads the ruling Liberal Democratic Party's task force on the abduction issue, said Japan should be tougher in dealing with the reclusive communist state.
"It has become clear that there is no point in continuing to negotiate with them the way we have been," he told reporters.