Born on July 14, 1923 in Bangkok, Suwat was a passionate writer, and produced a variety of works in short stories, novels, plays, TV drama, radio drama and movie scripts. He had several pen names, including S Voradilok, Phrai Visanu and Rapheeporn.

He was married to Phensri Phoomchusri. They had no children of their own, but adopted a child called Chatrachai Voradilok.

Suwat wrote in the same style as Sri Burapha and Seni Saowaphong, fighting against the powers that be, defending the underprivileged and promoting social justice.

His well-known books include "Philap Daeng" (Red Pigeon) and "Rajinee Boad" (Blind Queen).

Chamaiphorn Saengkrachang, president of the Thai Writers' Association, said: "He was a National Artist and a pillar to those of us in literary circles. He had a very firm standpoint, and a clear goal of how he would lead his life. He was also an idealist. His death is a big loss to Thailand."

Veera Rojpojanarat, permanent secretary of the Culture Ministry, said: "Suwat was a writer in the classical sense. He had the best command of language and he could reflect Thai society in its evolutionary form."

Suwat had been suffering from poor health, with a combination of heart disease and diabetes. He was living at his Sri Racha home in Chon Buri, where he was confined to bed.

Nivet Kanthairaj, a writer, paid Suwat a courtesy visit on Sunday to wish him well for the Thai New Year. Nivet said Suwat did not show any sign of being seriously ill, although he had to stay in bed.

Suwat's body will be brought to Wat Makutkasatiyaram today for the funeral service.