SINGAPORE - Singapore's longest-serving president S R Nathan has died peacefully at Singapore General Hospital at 9.48pm, the Prime Minister's Office said in a statement on Monday night (Aug 22). He was 92.

"The Prime Minister and his Cabinet colleagues are sad to learn of the passing of Mr S R Nathan and would like to convey their condolences to his family," the statement said.

"Arrangements for the public to pay respects and for the funeral will be announced later."

Mr Nathan, who turned 92 last month (July), had suffered a stroke on July 31, and was in critical condition.

President Tony Tan Keng Yam, Prime Minister Lee Hsien Loong, and Deputy Prime Minister Teo Chee Hean paid their tributes and offered condolences to Mr Nathan's family in Facebook posts.

Mr Nathan was Singapore's sixth and longest-serving president, occupying the highest office of the land from 1999 to 2011.

Prior to serving as head of state, he had a distinguished 40-year career in public service that took him through the worlds of trade unions, security, and diplomacy.

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In 1962, he joined the NTUC's Labour Research Unit, handling negotiatons between trade unions and employers at a time when labour unrest was widespread and pro-communist elements had infiltrated many unions.

Mr Nathan also had two stints at the Ministry of Foreign Affairs from 1961 to 1971 and from 1979 to 1982, the second as First Permanent Secretary.

He led the Security and Intelligence Division from 1971 to 1979, and secured the release of hostages from the hijacked ferryboat Laju by accompanying the hijackers on a flight to Kuwait to guarantee their safe passage.

After Mr Nathan retired from the civil service in 1982, he became executive chairman of media company The Straits Times Press (1975), the predecessor of Singapore Press Holdings.

He was later appointed High Commissioner to Malaysia from 1988 to 1990, and Ambassador to the United States from 1990 to 1996.

Upon his return from the US, Mr Nathan was made Ambassador-at-Large and Director of the Institute of Defence and Strategic Studies (IDSS) at the Nanyang Technological University.

Just as he was preparing for retirement, he was asked to run for president in Singapore's second presidential election. In 1999, he was elected unopposed to the first of two terms.

He was the first elected president to give approval for the Government's drawdown of the nation's reserves in 2009 amid a global financial crisis, a key power vested in the institution when it was introduced in 1991.

Mr Nathan leaves behind his wife Urmila, son Osith and daughter Juthika, and three grandchildren.