SEOUL -- South Korean officials said Monday they expected the United States to show up in Beijing this week for the first talks with North Korea since the nuclear crisis erupted six months ago.

The talks were thrown into doubt after Pyongyang angered Washington by indicating that it had begun, or was about to begin, reprocessing spent nuclear fuel rods to make weapons-grade plutonium.

Despite the announcement, U.S. President George W. Bush said Sunday that the United States, Japan, South Korea and China together had a "a good chance" of convincing North Korea to abandon its nuclear weapons program.

Washington believes North Korea already has one or two bombs and could quickly produce several more through reprocessing.

Bush's sunny rhetoric was countered Monday by more Sabre-rattling from North Korea, which called on its people to get "combat ready" and prepare to annihilate U.S. invaders.

China is poised to host three-way negotiations in Beijing tentatively set to open Wednesday. A senior South Korean government official said the talks would go ahead as announced.

"The trilateral meeting will go ahead as planned," the official said on condition of anonymity.

South Korea President Roh Moo-hyun's foreign press spokeswoman Lee Jihyun also said she had heard no reports that the talks had been cancelled.

"As far as I know the talks will go ahead," she told AFP.

In his upbeat assessment of a volatile situation, Bush singled out China for praise, saying Beijing was now committed to help resolve the nuclear crisis.

"Now that they're engaged in the process it makes it more likely that's going to occur," said Bush, who has refused allied appeals for one-on-one talks between Washington and Pyongyang.

"The key thing on the North Korea agenda is China is assuming a very important responsibility" and acting on former president Jiang Zemin's pledge to work to keep the Korean peninsula free of nuclear arms, the U.S. leader said.

If the talks go ahead, they would see U.S. and North Korean negotiators sit down at the same table for the first time since the nuclear crisis erupted in October of last year.

Experts said there were contradictions in reports carried by the official Korean Central News Agency (KCNA) on Friday about the spent fuel rods from the North's Yongbyon nuclear plant.

An English-language KCNA report Friday quoted a North Korean Foreign Ministry spokesman as saying Pyongyang was "successfully reprocessing" more than 8,000 spent fuel rods. The Korean-language version monitored in Seoul said the process had reached "the point of reprocessing."

U.S. and South Korean officials said that based on a review of the different versions, North Korea may not yet have begun reprocessing the fuel rods.

Both the English and Korean versions, however, agreed that the talks would be essentially bilateral in nature, with China's role reduced to that of genial host.

South Korea, upset at being sidelined from the nuclear talks, agreed Monday to separate cabinet-level talks with North Korea in Pyongyang from April 27 to 29.

The North's offer came on Saturday after Pyongyang called for rice and fertilizer aid from South Korea, breaking a month-long freeze in official inter-Korean contact.

South Korean officials said that at talks, Seoul would raise concerns about North Korea's nuclear program.

For the past six months, Pyongyang has escalated the crisis over its nuclear ambitions, expelling UN inspectors, restarting a plutonium-producing reactor and pulling out of the Nuclear Non-Proliferation Treaty.

On Monday, North Korean newspapers carried official calls for bolstering the nation's defensive capabilities.

"All officers and men of the people's army ... always keep yourselves combat ready," KCNA reported the North Korean military as saying. "If enemies invade our inviolable sky, land and seas even an inch, destroy up the aggressors with merciless annihilating blows."