BANGKOK (AP), May 26 (TIWN)— Prem Tinsulanonda, who as an army commander, prime minister and adviser to the royal palace was one of Thailand's most influential political figures over four decades, died Sunday at age 98.

His death in a Bangkok hospital was announced by the government's Public Relations Department, confirming earlier unofficial reports in Thai media. Never married, he leaves no family survivors. Thai Princess Sirindhorn will preside over his initial Buddhist funeral rites on Monday.

Prem was best known for his long-standing devotion to the monarchy, especially the late King Bhumibol Adulyadej, who appointed him to his Privy Council immediately after Prem's eight years as prime minister, and named him head of that powerful advisory body in 1998, a position he held until his death.

Prem is credited by some scholars with establishing the unspoken primacy of the palace in Thailand's power structure, cementing a mutually beneficial alliance with the military.

He was prime minister from 1980 to 1988, and helped usher in a period of relative stability after a successful pro-democracy uprising against a military dictatorship in 1973, a counter-revolution and coup in 1976 and another coup in 1977, as well as edginess about communist takeovers in neighboring Indochina in 1975.