Vietnamese authorities have released a Catholic activist who served more than three years in prison, where he said he had to endure repeated beatings and humiliation.

Dau Van Duong, 26, was freed on October 2 after being convicted in May 2012 with three other Catholic youths who violated a provision in the law that bars the conduct of "propaganda against the State."

The youths had been caught distributing prodemocracy leaflets.

Rights groups say the ambiguous provision in Article 88 of Vietnam's penal code is usually used by the government to harass critics of the State, such as dissidents and bloggers.

Duong was sentenced to three and a half years in prison, but he was released on and placed on probation for 18 months.

The Catholic activist said he was relieved after his incarceration, adding that he felt lucky to be alive given the beatings he endured while in prison.

"I thank God that I'm still standing here today. I might have died at that time. My body hurt terribly, but I kept praying and recovered," Duong told Radio Free Asia's Vietnamese Service in an interview.

He recalled that his jailers allowed other prisoners to beat him up. On several instances, the attacks stretched from 10:00 P.M. to 4:00 A.M. the following day.

Duong spent the earlier part of his detention at Nghi Kim Detention Center before being transferred to Prison No. 5 in neighboring Thanh Hoa province. He was locked up with "drug dealers, robbers, and murderers." But he was also placed with other political prisoners, he added.

He said Prison No. 5 was more lenient compared to his previous detention, but there had been times prison guards "humiliated" him.

On one instance, prison guards confiscated his Bible for no apparent reason. Duong protested and staged a hunger strike for a week, threatening to extend his action.

One prison officer said all religious books were prohibited there. "I could only get it back after I was freed," he recalled being told by the jailer.

"I told him that he had violated my right to religious freedom—a basic right for everyone, and that I would continue my hunger strike until he returned my Bible," he continued.

"One day after that, the management board convened and they returned my book, so I stopped my strike."

Duong was arrested in August 2011 for handing out flyers that urged people to boycott the Nghe An People's Council elections, saying the polls did not reflect the people's will.

He pointed out that candidates in the elections are handpicked by the ruling Communist Party of Vietnam.

Duong's fellow accused Tran Huu Duc got three years and three months in prison and Chu Manh Son was sentenced to three years at their trial in May 2012. A fourth defendant, Hoang Phong, was put on probation for 18 months.

Viet Nam has more than six million Catholics and is the second largest religion in the country, after Buddhism.