North Korean leader Kim Jong-il has died at the age of 69, state-run television has announced.

Mr Kim, who has led the communist nation since the death of his father in 1994, died on a train while visiting an area outside the capital, the announcement said.

He suffered a stroke in 2008 and was absent from public view for months.

Pyongyang described his son Kim Jong-un as the "great successor" and urged North Koreans to unite behind him.

"All party members, military men and the public should faithfully follow the leadership of comrade Kim Jong-un and protect and further strengthen the unified front of the party, military and the public," North Korea's state-run news agency, KCNA, said.