The 67-year-old North Korea leader Kin Jong II was diagnosed with pancreatic cancer and was expected to live no more than five years, South Korean broadcaster YTN said on Monday, citing unidentified sources from Chinese and South Korean intelligence officials.
Monday's report came after Kim last Wednesday made a rare public appearance in an annual memorial ceremony for his father and state founder Kim Il Sung.
Television footage showed him markedly thinner and with less hair. It was only the second state event he has attended in person since he was suspected of suffering a stroke a year ago.
Kim's health is one of the most closely guarded secrets in the reclusive state. There has never been official confirmation of him falling ill.
YTN said the diagnoses of the cancer came around the same time as the stroke.
South Korea's National Intelligence Service declined to confirm the reports and the Unification Ministry said it had no information to back up the report. U.S. officials did not immediately have comment.
While North Korea experts said the latest images of Kim show he is still fit enough to rule.