Abdul Ghani Othman, chief minister of the southern state, announced the sultan's death late Friday after he was admitted to a local hospital the day before for an unspecified illness, state news agency Bernama said.
"The sultan of Johor was very much respected and loved," Abdul Ghani said, reading a statement on TV, according to Bernama. He said the sultan died at 7:15 pm (1115 GMT).
A senior aide to the chief minister confirmed the sultan's death and that the sultan's eldest son, Tunku Ibrahim Ismail, had been appointed regent. He is expected to be named as sultan shortly.
Sultan Iskandar was born in 1932 and educated in Australia and Britain before joining the state civil service.
He took over as sultan of Johor in 1981, following the death of his father and served as Malaysia's king from 1984 to 1989.
Malaysia has a rotational monarchical system in which each state sultan takes turns to serve for five years as king.
Local papers were filled with tributes to Sultan Iskandar, calling him a "selfless ruler at heart" and "a ruler close to his subjects."
Premier Najib Razak cut short a state visit to India, returning to Malaysia early Saturday for the Sultan's funeral, Bernama reported.
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