Malaysia's King Sultan Salahuddin Abdul Aziz Shah is dead at the age of 75 years. He was the 11th in a series of rotating kings in the unique constitutional monarchy of Malaysia.

King Sultan Salahuddin died Wednesday in Kuala Lumpur after a lengthy illness. He had spent two months in a hospital in neighboring Singapore under treatment for a heart problem, but returned home Sunday after his condition worsened. Prime Minister Mahathir Mohamad made the announcement, saying "Malaysia will hold a day of national mourning. Sultan Salahuddin was one of nine Malaysian sultans, or traditional state monarchs, who take turns as king of Malaysia. He took up the mostly ceremonial post in April 1999."

Under a system established in 1957, the sultans choose a king to serve a five-year term. The sultans are briefed periodically on affairs of the state by the prime minister, who is the senior political leader. Although the sultans' functions are primarily ceremonial, Malaysians say they provide continuity and wield considerable traditional and religious influence behind the scenes.

Sultan Salahuddin was Sultan of Selangor, a state surrounding the capital, Kuala Lumpur. He became sultan in 1960, upon the death of his father. He was the eighth sultan in a dynasty that stretches back nearly 250 years.

Sultan Salahuddin was born in 1926 in Kuala Langat. He attended the Malay College and studied for two years at London University's School of Oriental and African Studies.

In the 1950's, he served in the public services department of what was then the British colony of Malaya and subsequently became a school inspector. In 1952, he was commissioned as a captain in the Malay Regiment and was promoted to major.

He is to be succeeded as Sultan of Selangor by his son, the crown prince Tengku Idris Shah.