North Korean leader Kim Jong-Il is reportedly suffering from kidney failure which requires dialysis and also has partial paralysis following a 2008 stroke.
Nam Sung-Wook, director of the Institute for National Security Strategy, said the paleness of Kim's fingernails indicates the 68-year-old leader has chronic kidney disease.
The institute has links to South Korea's National Intelligence Service. Nam's remarks, in a speech at a Seoul forum, were quoted by Yonhap news agency and were confirmed by the organisers of the event.
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"Chairman Kim Jong-Il is suffering from diabetes and high blood pressure and we believe he is undergoing kidney dialysis every two weeks," Nam said.
"(The pale colour of) his nails indicates he has chronic kidney failure."
Nam showed photographs of Kim to illustrate his point. The North's official Korean Central News Agency frequently releases colour photos of the leader.
Kim weighed 86kg before his stroke in August 2008, according to Nam. In January last year he went on a three-month diet and slimmed down to 70-73kg.
"However, it's not an easy task for him to restore his full health because of his age," Nam said.
"At his most recent public appearance on the occasion of a public rally in (the northeastern city of) Hamhung on March 7, he was slamming down his right palm on his unmoving left palm."
The leader of the secretive nuclear-armed communist state has not publicly appointed an eventual successor, but the regime is reportedly promoting the virtues of his third son Jong-Un.
"But as it would be like having two suns in the sky and there was controversy over Jong-Un's intervention in personnel appointments, such a movement has subsided somewhat since June last year," Nam said.
Kim's regime is under pressure to return to six-nation nuclear disarmament talks which it abandoned last April. But Nam foresaw no early progress.
"The date for the next round of the six-party talks is unlikely to be fixed before June, as efforts to resume the talks have not yet led to any concrete results," he said.
