North Korea agreed to a new round of six-nation talks next week aimed at dismantling its nuclear weapons programs, officials announced Tuesday. But representatives of the four Asian countries involved immediately sought to play down the prospects of a quick resolution to the 20-month crisis in which the North Koreans are believed to have expanded their nuclear arsenal.

High-level disarmament talks are scheduled for June 23-26 in Beijing, after a two-day round of mid-level negotiations starting June 21, according to Chinese, Japanese and South Korean officials.

The talks -- involving the United States, China, Russia, Japan, South Korea and North Korea -- follow two rounds of high-level negotiations and one round of mid-level meetings, which all failed to yield significant results.

Since the nuclear issue erupted in October 2002, U.S. intelligence has increased its estimates of North Korea's military capabilities from possessing as many as two to as many as eight nuclear devices. But few diplomats held out hope for speedy progress. In a sign of how low expectations are running, even officials from the participating nations appeared to see little immediate promise of a breakthrough.

"The Korean Peninsula's nuclear problem is very complicated," Zhang Qiyue, a Chinese Foreign Ministry spokeswoman, told reporters in Beijing. "It is very difficult for any side to expect to resolve all the issues in one round or two rounds of talks."

The Bush administration is locked in a stalemate with the North Korean leader Kim Jong Il over U.S. calls for the complete, verifiable and irreversible dismantling of all of the Pyongyang government's nuclear weapons programs, known as CVID. For their part, North Korean officials have offered a partial freeze of the programs -- and then only if financial and diplomatic incentives are provided upfront, something the Bush administration has dismissed.

The search for common ground to date has left the two key parties -- the United States and North Korea -- drifting further and further apart. At the same time, North Korea seems to be enjoying a measure of success in its strategy of dividing the five nations seeking its disarmament, observers have said.

Chinese authorities, for instance, expressed new doubts about the U.S. stance that North Korea possesses a uranium enrichment program in addition to its admitted program to enrich plutonium for use in nuclear weapons. The U.S. government has insisted that North Korea's public admission of the existence of the uranium program is key to any agreement.

Alarmed that Kim is advancing with his nuclear ambitions while the talks have stalled, the closest U.S. allies in Asia -- Japan and South Korea -- have also moved independently to engage the government in Pyongyang in bilateral talks, an approach the Bush administration has rejected.

Japan's Prime Minister Junichiro Koizumi held a summit with Kim last month, offering him $10 million in humanitarian aid in exchange for the release of five children of Japanese nationals abducted by North Koreans for use in spy training camps during the 1970s and 1980s. South and North Korea, meanwhile, have forged ahead with high-level military talks which resulted in a series of agreements this month to ease tensions along the most heavily militarized border in the world as well as to open new roads and rail lines linking the divided nations by this fall.

North Korea's success in negotiations with Japan and South Korea -- and continuing brisk economic trade with China -- may have emboldened Kim to avoid giving any major concession next week, according to analysts. Instead, the North Koreans may offer more limited promises -- or nothing at all -- to bide time until U.S. presidential elections in November, analysts have said. Sen. John F. Kerry of Massachusetts, the presumed Democratic candidate, has said he favors engaging the Pyongyang government directly in bilateral talks.

During the last round of talks in February, South Korea presented a phased proposal to resolve the crisis, starting with a "temporary halt" -- essentially a freeze -- to North Korean nuclear programs. A halt, once verified, would be followed by a South Korean promise, already accepted by China and Russia, to ship heavy oil to North Korea. The United States would join the other parties at the table in offering North Korea security assurances.

But that plan failed in part because the North Koreans refused to admit to the uranium program. According to U.S. officials, the North privately acknowledged in October 2002 that it had a program, in violation of a 1994 agreement with the Clinton administration. But South Korean officials familiar with the talks also said U.S. negotiators refused North Korean requests to broadly outline what type of rewards it might receive if it agreed to a halt.

South Korea is still pushing its plan, but there is little sense that either the United States or North Korea has budged.

"We have no indication to demonstrate that the U.S. has become more flexible," Jiro Okuyama, spokesman for Japan's Foreign Ministry, said in an interview. He said Japan still "closely shared" the U.S. position, and would continue to press North Korea for a complete, verifiable and irreversible dismantling.

North Korea has also vacillated on what it would do. Last month, Kim appeared to draw a step closer to compromise during his summit with Koizumi by offering what the Japanese described as a "verifiable freeze" of his country's nuclear efforts. But North Korea's official news agency KCNA on Tuesday reverted to its old line that any freeze must also carry a "reward.".

Special correspondent Sachiko Sakamaki contributed to this report.