( L - R ) Bush and Liu

SEOUL (Reuters):

North Korea threatened Japan yesterday with 'strong countermeasures' if it goes ahead with tougher sanctions over Pyongyang's reported nuclear test.

Japan and the United States are pushing for tough measures against the North, although diplomats say China opposes the more punitive parts of a draft resolution Washington wants the United Nations Security Council to adopt in a vote.

"We will take strong countermeasures," said Song Il-ho, North Korean ambassador in charge of diplomatic normalisation talks with Japan, according to a report by Japan's Kyodo news agency from Pyongyang.

"The specific contents will become clear if you keep watching," Song said. "We never speak empty words."

Japan, arguing that Pyongyang's nuclear weapons poses a direct threat to its safety, is expected to formally approve additional sanctions today, including banning imports from the impoverished communist state and blocking North Korean ships from entering Japanese ports.

U.S. President George W. Bush, speaking after Japan announced plans for extra sanctions, said on Wednesday: "In response to North Korea's actions we're working with our partners ... to ensure there are serious repercussions for the regime in Pyongyang,"

China, the nearest North Korea has to an ally, has flatly condemned its communist neighbour and backs limited sanctions but diplomats said it sees the U.S. approach as too stringent.

"One can say that punishment isn't the goal," Chinese Foreign Ministry spokesman Liu Jianchao told reporters yesterday, saying any sanctions would be to coax North Korea back to talks.

There has so far been no independent confirmation that Monday's explosion was in fact the result of a nuclear device. Some have speculated that even if it was, it might not have been as successful as Pyongyang claimed.

North Korea has brandished the threat of more tests, calling U.S. pressure to rein in its nuclear programme tantamount to a "declaration of war".