Powell, who will meet President Roh Moo-Hyun and other senior officials during the last leg of his three-nation Asian tour, wants to forge a joint strategy with Tokyo, Beijing and Seoul to get Pyongyang to return to the table unconditionally.

Despite apparent success on his first two stops, North Korea shows no sign of dropping its boycott of the talks and is threatening to bolster its military deterrent to counter "hostile" US acts.

In both Japan and China, Powell rejected Pyongyang's claims of Washington's aggressive attitude but also dismissed its demands for up-front rewards for returning to the six-party talks.

After being offered a US aid-for-disarmament package at the last round of the Beijing-hosted talks in June, North Korea refused to attend a fourth meeting in September -- citing belligerence by the United States.

Shortly before Powell arrived in South Korea late Monday, a senior State Department official said China had signalled to Powell that it would intensify its efforts to persuade North Korea to rejoin the talks.

"It is my opinion that the Chinese will use their combination of influence and try to get the dialogue to resume as soon as possible and certainly within the next couple of months," the official said on condition of anonymity.

After meeting Chinese President Hu Jintao, Premier Wen Jiabao and Foreign Minister Li Zhaoxing, Powell himself said he was hopeful China would use its influence with North Korea.

"I hope as a result of conversations today, both of us will energize the other members of the six-party framework to resolve the outstanding issues that keep us from setting a date for a meeting," he told reporters in Beijing.

After Powell's meetings in Japan on Sunday, Tokyo agreed to push Pyongyang to return to the talks during working-level meetings next month with North Korean officials to discuss the Cold War-era abduction of Japanese citizens.

The same day, though, North Korea accused the United States of paying only "lip service" to a peaceful settlement of the nuclear deadlock. It blasted a US-led joint naval exercise off the Japanese coast as a sign of US antagonism.

Pyongyang criticised the exercise again when it began on Monday, denouncing it as an attempt at a maritime blockade and a "serious infringement" of its sovereignty that would dim prospects for a negotiated settlement to the nuclear impasse.

"These moves only make the prospect of the negotiations ... dimmer as the days go by," the official Korean Central News Agency said. "Dialogue can never go together with war exercises."

The drill, which is being held under the auspices of President George W. Bush's Proliferation Security Initiative (PSI), is designed to practice techniques for seizing illicit weapons cargos on the high seas.

Although one stated goals of PSI is to prevent the spread of weapons of mass destruction by and to North Korea, Powell denied the manoeuvers were aimed at Pyongyang and said it need only worry if it is involved in illicit shipments.

He also rejected Pyongyang's complaints about a new US human rights law aimed at North Korea, saying the matter was a valid concern and desperate North Koreans were "speaking out" about abuses by fleeing the country.

As Powell began his meetings in China, a group of North Korean refugees proved his point by attempting to enter a South Korean consulate building in Beijing.

In addition to discussing the North Korea issue in Seoul, Powell will be talking to officials including Foreign Minister Ban Ki-Moon and Unification Minister Chung Dong-Young about the redeployment of US troops in South Korea.

The United States plans to withdraw a third of its 37,000 troops from South Korea by the end of 2008, taking the US military presence on the peninsula to its lowest level since the 1950-1953 Korean war.

Washington initially proposed withdrawing the 12,500 troops from the peninsula next year, but agreed in negotiations to stretch the pullout over four years in response to South Korean concerns.