Gustavo Arcos, Requiescat in pace.

HAVANA - Gustavo Arcos Bergnes, a comrade of Fidel Castro in the early days of the revolution but later imprisoned for criticizing the regime, died of a heart attack here, opposition activists told AFP. He was 79.

Arcos was "a symbol of the opposition, the dean of the opposition," said another opposition figure, Marta Beatriz Roque, who got the information from Arcos's wife.

Arcos was a law student when he participated in the July 26, 1953 assault on the Moncada military base in Santiago de Cuba, the incident that sparked the Cuban revolution.

"He fought against (dictator Fulgencio) Batista and now he was fighting the tyranny of Fidel Castro," Roque said.

After the revolution triumphed in 1959, Arcos became ambassador to Belgium, but became increasingly critical of the regime and resigned in 1964. He returned to Cuba and was imprisoned from 1966 to 1969, and again from 1982 to 1988.

In a 2003 interview with AFP, Arcos said he had no regrets.

"I followed the ideals that guided us in those times, which were to eliminate the Batista regime and re-establish democracy."

Arcos's wife Teresita Rodriguez said recently that in the last weeks her husband had weakened considerably.

He founded the Cuban Pro-Human Rights Committee along with his brother Sebastian and two other dissidents, Ricardo Boffil and Elizardo Sanchez, in 1988.

Arcos, the eldest of Cuba's dissidents, entered the hospital on July 18, suffering from pneumonia and a urinary infection.

"He had pneumonia and died from respiratory failure," Roque said.

"He was in the hospital and he never went home, because his condition was very bad," said Roque. (Thanks to AFP for this obituary.)