North Korea's long-time leader Kim Jong Il has died of heart failure.
In a special broadcast from the North Korean capital, Pyongyang, state media said Kim died of a heart ailment on a train due to a "great mental and physical strain" on December 17, during a "high intensity field inspection". The broadcast said a post-mortem examination was carried out on December 18 and "fully confirmed" the diagnosis on the 69-year-old.
North Korea said Kim's body will be placed in the Kumsusan memorial palace in Pyongyang and there will be a national mourning period until December 29. Kim's funeral will be held on December 28.
The communist country's "Dear Leader" - reputed to have had a taste for cigars, cognac and gourmet cuisine - was believed to have had diabetes and heart disease.
South Korea launched a high alert for its military as it faces the North's 1.2 million-strong armed forces, while President Barack Obama and South Korean President Lee Myung-bak agreed by phone to monitor the events closely and co-operate.
"He passed away too suddenly to our profound regret," said a statement carried by the North's official Korean Central News Agency. "The heart of Kim Jong Il stopped beating, but his noble and august name and benevolent image will always be remembered by our army and people."
While there was no immediate statement on official succession, there were clear indications that Kim Jong Un would be in charge.
The North said in a dispatch that the people and the military "have pledged to uphold the leadership of comrade Kim Jong Un" and called him a "great successor" of the country's revolutionary philosophy of juche, or self reliance.
"At the leadership of comrade Kim Jong Un, we have to change sadness to strength and courage and overcome today's difficulties," North Korea said.
It was not immediately clear what effect Kim's death would have on recent efforts to bring North Korea back into nuclear talks aimed at exchanging aid for commitments by the North to disarm. Asian stock markets moved lower after the news, which raises the possibility of increased instability on the divided Korean peninsula.
