SEOUL - ALL three of North Korean leader Kim Jong Il's known sons have chronic illnesses with the youngest suffering from hypertension and diabetes, a news report said on Wednesday.

The reclusive 66-year-old leader may have suffered a stroke in recent weeks, South Korean officials have said, raising questions about succession in Asia's only communist dynasty.

Mr Kim has not openly indicated if any of his sons will succeed him, but that has not stopped several analysts from speculating which one may be next in line for the leadership.

Mr Kim's oldest son, Jong Nam, 37, suffers from heart problems, like his father and grandfather, Yonhap news agency quoted sources familiar with the North as saying.

Jong Nam, seen frequently in the media during travels through Beijing and Macau, is also severely overweight.

The second son, Jong Chol, believed to be 27, is thought to be suffering from a hormonal disorder and may even be addicted to painkillers that he started taking after hurting his leg playing basketball, they said.

Jong Un, 25, described by intelligence officials as the most capable, 'may have seen his health worsen sharply after he took to drinking heavily out of stress,' the sources were quoted as saying.

South Korea's spy agency would not comment on the report.

All of Mr Kim's known sons have left secretive North Korea for several years to live and study abroad.

North Korean leader Mr Kim Jong Il has long been suspected to be suffering from heart problems and diabetes, intelligence sources have said.

In rare comments at an inter-Korean summit in 2007, Mr Kim dismissed the reports as 'fiction' and said he was in good shape.

Mr Kim's father, the patriarch and the founder of the communist state, Kim Il Sung, died in 1994 of a heart attack at 82. -- REUTERS