The releases come after Venezuela's interim President Delcy Rodriguez on Friday announced a proposed "amnesty law" for hundreds of prisoners, and said the Helicoide detention centre in Caracas would be converted into a centre for sport and social services.
A 2022 United Nations report said prisoners in Helicoide were subjected to torture, an accusation the government rejected.
Rights group Foro Penal said it had verified that 344 "political prisoners" had been freed since the government announced the new series of prisoner releases in early January, 33 of them on Sunday.
Government officials - who deny holding political prisoners and say those jailed have committed crimes - have put the total number of releases much higher at more than 600, though that figure appeared to include releases from prior years.
Among those freed on Sunday was human rights activist Javier Tarazona, who had been in prison since mid-2021 in the Helicoide centre.
"After 1,675 days, four years and seven months, the day we've so wished for has arrived, my brother Javier Tarazona is free," Jose Rafael Tarazona said on X. "The freedom of one is hope for all."
Tarazona is the director of FundaRedes, which tracks alleged abuses by Colombian armed groups and the Venezuelan military along the countries' border. He was arrested and accused of terrorism and conspiracy.
Prisoner releases have accelerated since Venezuela announced a release policy on January 8, in the wake of the US capture of former President Nicolas Maduro.
"Every step towards freedom and the definitive end of repression is important," Gonzalo Himiob, vice president of Foro Penal, said on X.
The Venezuelan communications ministry, which handles press queries, did not immediately respond to a request for comment.
Foro Penal has said more than 300 political prisoners have been released in recent weeks and estimated that more than 700 remain jailed.
The government has not said how many prisoners will be released or identified them.
Families of prisoners say the releases have progressed too slowly, and relatives and human rights advocates have demanded that charges and convictions against detainees who are considered political prisoners be expunged.
Nobel Peace Prize winner and opposition leader Maria Corina Machado, who has several close allies imprisoned, has advocated for their release.
Prominent figures still detained include opposition politician Juan Pablo Guanipa and lawyer Perkins Rocha, both close Machado allies, and opposition Voluntad Popular party leader Freddy Superlano.
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