Talks on ending the North Korean nuclear crisis hung in limbo Monday: North Korea (search) blamed the impasse on Washington's demand for disarmament, and South Korea and Russia said it was unlikely a new round of six-nation negotiations could open this month.

Amid the standoff, Russian and Chinese diplomats met in Moscow on Monday to discuss a compromise solution that first freezes North Korea's atomic programs, then rolls them back. The two issued a joint call for a new round of talks to be held soon.

The developments come as a delegation of U.S. congressional aides headed to North Korea to possibly tour the communist country's disputed nuclear plant at Yongbyon (search). The two staffers will then visit the South Korean capital of Seoul over the weekend, U.S. Embassy Spokeswoman Maureen Cormack said.

The Yongbyon complex is at the heart of the standoff, and there has been no outside access to the facility since North Korea expelled U.N. nuclear inspectors at the end of 2002.

The two Koreas, the United States, Russia, China and Japan have been trying to resume a second round of talks for months, aimed at persuading North Korea to abandon its nuclear weapons programs. A first round of talks in Beijing in August ended with little progress.

There were hopes a new round could open early this year, after differences between the United States and North Korea prevented more negotiations before the close of 2003. But in Moscow, a leading Russian diplomat said talks would probably not happen this month — again, because of Washington and Pyongyang.

Deputy Foreign Minister Alexander Losyukov blamed the delay on disagreements over the wording of a final document for the talks. He said efforts to set up more talks were "very difficult" and that a final document could not be forged because of "mistrust and increased demands on each other" by the United States and North Korea, according to Russia's Interfax news agency.

South Korea's National Security Adviser Ra Jong-il also said a new round was unlikely to happen this month — but blamed scheduling conflicts with the Russian Christmas holiday and the Chinese Lunar New Year, both in January.

North Korea says it will dismantle its nuclear programs in exchange for a U.S. security guarantee and aid. But before making any concessions, Washington wants North Korea to give up its nuclear ambitions.

North Korea on Monday blamed Washington's stance for the delay in scheduling a new round of talks and rejected as unfair U.S. demands that it first irreversibly and verifiably disarm.

A commentary in the North's official KCNA news agency accused Washington of seeking to "completely disarm the DPRK and destroy it by the tactics of throttling it to the last." DPRK stands for Democratic People's Republic of Korea, North Korea's official name.

As a first step, North Korea again offered to freeze, not reverse, its nuclear programs.

"The actions to be taken at the first phase are for the U.S. and the neighboring countries to take measures in return for the DPRK's complete freeze of its nuclear activities. This is a starting point and a core issue of furthering the process of talks," KCNA reported, adding that the "ball is in the U.S. court."

In Moscow, China's newly appointed envoy on North Korea, Ning Fukui, met with the head of a Russian Foreign Ministry department for Asia, Yevgeny Afanasyev. Losyukov met with both men, Russian news agencies reported.

Afterward, ITAR-Tass reported that both nations repeated support for "a nuclear-free Korean peninsula in the interest of peace and stability" for all nations in the region.

Russia's Foreign Ministry said that to achieve that aim, China and Russia "mutually expressed interest in quickly holding the second round of six-nation talks," ITAR-Tass said.

Russia and China are working on a compromise that assumes the liquidation of the North Korean nuclear program may take more than one year. Agreement to a "freeze" of nuclear work by Pyongyang would be the first step toward dismantlement, according to ITAR-Tass.

The North Korean nuclear crisis flared in October 2002 when U.S. officials accused North Korea of running a secret nuclear weapons program in violation of a 1994 deal in which North Korea is obliged to freeze its nuclear facilities. Washington and its allies cut off free oil shipments, also part of the 1994 accord.