Kim Jong-il, North Korea's top leader who ambitiously pursued a nuclear weapons programme, died Saturday during a train journey "from a great mental and physical strain". He was 69, the country's official KCNA news agency announced Monday.

On learning about Kim's death, South Korea promptly put its security forces on high alert as Washington said it was in touch with Seoul and Tokyo, reports Xinhua.

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AFP PHOTO / KCNA via KNSu00a0