South Korea's foreign minister on Tuesday urged China to use its influence over Pyongyang to dissuade the North from apparent plans to launch a long-range missile test, as the two countries agreed to step up diplomatic efforts to resolve the issue. But Western diplomats questioned China's willingness to wield its influence over North Korea.

South Korea's Ban Ki-moon and his Chinese counterpart Li Zhaoxing held closed-door talks for about an hour, discussing strategies to sway Pyongyang not to test-fire a missile and resume six-nation talks on North Korea's nuclear weapons program.

"We should focus efforts on dissuading North Korea from test-firing a missile," Li said.

Ban urged China to persuade North Korea against testing the missile, South Korea's Yonhap news agency reported, citing Lee Hyuck, director-general of the South's Foreign Ministry's Asia-Pacific affairs bureau. Lee attended Tuesday's talks.

China, a key provider of aid to impoverished North Korea, is believed to be the only country that has considerable leverage with the hard-line regime of Kim Jong Il. But since the crisis over North Korea's nuclear programs emerged in late 2002, China has largely refrained from threats to halt the fuel and food deliveries and bank credits that sustain Pyongyang.

Six-nation talks aimed at resolving the issue of North Korea's nuclear program have been stalled since November over a dispute surrounding U.S. financial restrictions on the North.

Western diplomats in Beijing, who spoke on customary condition of anonymity, said China had not sent a special envoy to Pyongyang or otherwise intensified its diplomacy over the missile threat.

Li told Ban that getting North Korea back to talks on its nuclear weapons ambitions was a top priority and that efforts should be focused on ensuring Pyongyang avoids firing a missile. Li said Beijing had discussed the reported missile test plans with Pyongyang, Yonhap said, but did not give details.

Ban left Beijing Tuesday evening to return to Seoul, following a meeting with the Chinese Cabinet's chief foreign affairs minister, State Councilor Tang Jiaxuan.

Meanwhile, North Korea on Tuesday said the United States was to blame for a "new nuclear arms race."

"The U.S. is the principal criminal of the present nuclear arms race, the very one who harasses world peace and security," the North's main newspaper Rodong Sinmun said in a commentary, according to the official Korea Central News Agency.

"The U.S. should give up its wild ambition for nukes, mindful that its nuke modernization and space militarization will be a grave crime of disturbing world peace and security," the newspaper said.

U.S. President George W. Bush said in Washington that North Korea should heed warnings by China and other nations not to test the ballistic missile.

Recent intelligence reports have said North Korea may be fueling a Taepodong-2, one of its most advanced missiles, at a launch site on the country's northeastern coast. The missile is believed to be capable of reaching parts of the United States.

Japan's Prime Minister Junichiro Koizumi headed Tuesday to the United States for talks with Bush on the North Korean ballistic missile issue, plus terrorism, security and the economy.

The North shocked the world in 1998 by firing a missile that flew over northern Japan and into the Pacific Ocean. It has been under a self-imposed moratorium on long-range missile tests since 1999, but has since test-fired many short-range missiles.

The Washington-based Institute for Science and International Security estimated in a report Monday that North Korea has enough separated plutonium to develop an arsenal of four to 13 nuclear weapons, compared with estimates of one or two nuclear weapons in 2000.

The group says that by 2008, North Korea could have enough plutonium for eight to 17 nuclear weapons. It also said North Korea was currently unlikely to be capable of making a nuclear warhead light enough for the Taepodong-2 missile.