Vice Marshal Jo Myong-Rok, 74, has been staying in a military hospital used by Chinese leaders since he flew into Beijing Monday, Yonhap news agency said, citing a source in Seoul.

Contacted by AFP, the hospital refused to confirm the report.

Yonhap said Jo had undergone a kidney transplant in China in 2001 and had received treatment at the same Beijing hospital in March and November last year.

The source told Yonhap: "His condition has so worsened that dialysis no more helps."

Jo, who also heads the politburo of the Korean People's Army, is nominally ranked third in the country's hierarchy behind Kim Jong-Il and Kim Yong-Nam, president of the presidium of the legislative Supreme People's Assembly.

He serves as first vice chairman of North Korea's highest decision-making body, the National Defense Commission (NDC) which controls the country's 1.1 million-strong armed forces.

Jo was last seen in public on September 17 when he accompanied Kim Jong-Il to attend a performance by a Russian army academic song and dance ensemble in Pyongyang.

Following a visit to North Korea by then US secretary of state Madeleine Albright in late 1999, Jo visited the United States as a special envoy of the North Korean leader and met president Bill Clinton.

Yonhap said in a separate report Tuesday that Yon Hyoung-Muk, another senior NDC official had surgery in Russia for pancreatic cancer in mid-November.

Yon, a former prime minister, was promoted to vice chairman of the NDC in September. In February 2002, he was reportedly treated in Russia for urinary problems.

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