Gustavo Arcos Bergnes, who fought alongside Fidel Castro in the Cuban revolution but was later imprisoned for counterrevolutionary activities, died Tuesday, according to a neighbor and the mortuary handling arrangements. He was 79.

Clara Villar, a neighbor of the Arcos family, and a woman who answered the phone at the Calzada and K mortuary nearby said Arcos died at 11:40 a.m. Tuesday in Havana. The cause of death was not immediately known, but Arcos had been hospitalized recently.

Born on Dec. 19, 1926, in the small central Cuban town of Caibarien, Arcos was studying diplomatic law at the University of Havana when he first met Castro.

Deeply opposed to the government of Fulgencio Batista, Arcos joined Castro's ill-fated 1953 assault on a military barracks that launched the Cuban revolution. Arcos was shot in the right hip and left partially paralyzed.

Imprisoned, the survivors were later freed under a pardon and Arcos traveled with the group to Mexico to organize a rebel army.

Known by the pseudonym "Ulises," Arcos traveled throughout Costa Rica, Venezuela and the United States gathering money and munitions for the movement.

The other rebels, meanwhile, traveled back to Cuba on the yacht "Granma" to launch a guerrilla war. Arcos' brother Luis was among those killed by Batista's forces when the boat landed.

Arcos was named Cuba's ambassador to Belgium after the 1959 triumph of the Cuban revolution, but soon became disillusioned by the growing authoritarianism of the Castro regime.

"They shot a lot of people," Arcos told The Associated Press in May 2005 of the summary trials held after the revolutionaries took power. "They shot people who could have easily been imprisoned."

By the time Arcos returned to Cuba in the mid-1960s, the government had turned socialist.

Arcos began expressing his discontent privately and was soon accused of being a counterrevolutionary. When he was released after three years in prison, the government refused his request to leave the country.

Arcos and his younger brother, Sebastian, became involved in the Cuban Committee for Human Rights, formed in 1978 as one of the first groups of its kind after Castro took power almost two decades earlier.

The Arcos brothers were imprisoned in 1981, for trying to leave the country illegally. Sebastian Arcos, who became a leading rights activist in his own right, died from cancer in 1997.

Shortly after his release from prison in 1988, Gustavo Arcos replaced the committee's executive director, who was forced into exile. In subsequent years, pro-government mobs occasionally gathered outside Arcos' home to chant insults.

Through the committee, Arcos issued reports about human rights complaints to international organizations and distributed copies of the Universal Declaration of Human Rights on the island.

Arcos leaves his wife, Teresa, who he married shortly after his final release of prison in 1988. He also told of having a son, from a previous relationship, and two granddaughters, all of the Miami area.

Born into a family of nine children, he also is survived by four sisters and a brother.

CountryWatch: Cuba