SEOUL, South Korea -- North Korean leader Kim Jong Il may die within three years, a senior U.S. envoy said in Seoul last month, according to a report published Wednesday.

Assistant U.S. Secretary of State Kurt Campbell told U.S. Ambassador Kathleen Stephens, a South Korean lawmaker and activists in a closed-door session that he doubted the 68-year-old leader would live beyond 2013, South Korea's Chosun Ilbo newspaper said.

Campbell based his estimate on medical information, the report said, citing unidentified sources.

U.S. Embassy spokesman Aaron Tarver said he had no details. Park Sun-young, an opposition lawmaker who attended the Feb. 3 meeting, said Wednesday that she had no comment.

A state-run South Korean think tank, the Korea Institute for National Unification, also said in a January report that Kim Jong Il probably wouldn't survive past 2012. It cited no specific evidence for the estimate.

The report comes amid speculation that the autocratic Kim is preparing to hand power over to a son.

Kim Jong Il is believed to have suffered a stroke in 2008, and has appeared noticeably gaunt in public appearances over the last year. His health is of keen interest because of concerns that his sudden death could trigger instability and a power struggle in the nuclear-armed communist country.

Kim, who himself inherited power in 1994 upon the death of his father, North Korean founder Kim Il Sung, has not publicly named any of his three sons to succeed him. However, he is said to favor his youngest son, the Swiss-educated Kim Jong Un, believed to be in his mid-20s.

Little is known about the son. U.S. officials were sent to question teachers at the Swiss school to find out more about him, the Chosun Ilbo report said, citing an unidentified participant in the meeting.

Campbell predicted the succession would be "totally different" from Kim Jong Il's ascension to power after being groomed for the post for many years.