Top Japanese and Chinese envoys held talks on North Korea's nuclear disarmament in Beijing on Tuesday amid high tensions on the Korean peninsula, Japanese news reports said.

Akitaka Saiki, chief of the Asian and Oceanian Affairs Bureau, arrived in Beijing Tuesday for a two-day trip and met his Chinese counterpart Wu Dawei at the Chinese foreign ministry, Jiji Press reported.

The two diplomats were expected to discuss China's proposal for "emergency consultations" in Beijing early next month among chief envoys to the stalled six-nation talks on Pyongyang's nuclear disarmament.

Tensions have spiked on the divided peninsula after the North last week shelled a South Korean border island, killing four people and wounding 18 in the first bombardment of a civilian area in the South since the Korean war.

China, Pyongyang's sole major ally, has stressed that the proposal did not constitute a formal resumption of the negotiations, but says it hopes they would lead to such a resumption soon.

Japan has expressed reluctance over the talks, saying it cannot be "positive towards consultations" unless the North faces up to its responsibility for the attack and its nuclear activities.

"We don't deny the six-party dialogue itself," Foreign Minister Seiji Maehara told reporters. "But if we gather, some kind of progress should be made based on the past agreements of the six-party talks. That's our stance."

But Pyongyang, on Tuesday, moved to escalate tensions by boasting about the sophistication of its new uranium enrichment plant, a facility that has raised fears the regime wants to make more fuel for atom bombs.

World powers fear that the volatile regime of Kim Jong-Il, which has twice tested atom bombs, is seeking to produce weapons-grade uranium on top of the plutonium it already has to use in a game of nuclear brinkmanship.

The White House on Monday brushed aside China's call for new six-nation talks on North Korea, saying it would amount to "PR activity" unless Pyongyang changed its behaviour. South Korea and Russia are also involved in the six-party talks but Washington has urged North Korea to stop what it describes as provocative behaviour before they can resume.

Details of a meeting between Maehara, South Korea's Foreign Affairs and Trade Minister Kim Sung Hwan and US Secretary of State Hillary Clinton, were also under discussion, Tokyo said Tuesday.

"This is an initiative taken by State Secretary Clinton," Chief Cabinet Secretary Yoshito Sengoku told reporters. "I hear that its schedule is being arranged now. The Japanese government will take part in it proactively and hopes that the meeting will deepen the cooperation among Japan, South Korea and the United States in more specific and practical ways."