DUBAI, United Arab Emirates (AP) — Bahrain's king pardoned 457 prisoners Wednesday night to mark his 25th anniversary as the island nation's ruler, with one activist saying many of those freed appeared to be political prisoners.

The announcement by the state-run Bahrain News Agency marks another mass release of prisoners in the Persian Gulf kingdom that has experienced repeated crackdowns on all dissent in the years following its 2011 Arab Spring protests.

There was no list of names of the prisoners released by the order of King Hamad bin Isa Al Khalifa, who has ruled Bahrain first as its emir in 1999 before Bahrain became a kingdom in 2002.

Bahrain's government did not answer questions from The Associated Press, but said the pardon "further demonstrates Bahrain’s commitment to criminal justice, with an opportunity today for over 450 individuals to positively re-integrate back into society."

Sayed Ahmed Alwadaei, who serves as the director of advocacy for the Bahrain Institute for Rights and Democracy, described many as being political prisoners now freed from the Jaw Rehabilitation and Reform Center. The prison has seen demonstrations and hunger strikes by prisoners over conditions there.

“Authorities have been meeting with ... hundreds, saying to them they would be released very soon,” Alwadaei said. “It seems to be targeting mostly political prisoners.”

He added: “This is a really optimistic step and it does seem to be also coming within a regional context where Bahrain is trying to normalize with Iran.”

Bahrain’s Shiite majority long has complained about mistreatment and abuse from the government overseen by the ruling Sunni Al Khalifa family. Addressing activists’ complaints could help Bahrain ease tensions with Iran despite decades of enmity, particularly after Saudi Arabia reached a Chinese-mediate detente with Tehran last year.

In April, King Hamad pardoned 1,584 prisoners, including over 650 considered to be political prisoners by the institute.

Prominent Bahraini activists being held include Abdulhadi al-Khawaja, a dual Danish Bahraini national convicted of internationally criticized terrorism charges and held in what a United Nations panel calls an “arbitrary” imprisonment ever since.

Bahrain, home to the U.S. Navy’s Mideast-based 5th Fleet, is an island off the coast of Saudi Arabia that’s about the size of New York City with a population of around 1.5 million people.

Since Bahrain put down the 2011 protests with the help of Saudi Arabia and the United Arab Emirates, it has imprisoned activists, deported others, stripped hundreds of their citizenship and closed its leading independent newspaper.

Meanwhile, Bahrain has recognized Israel diplomatically and hosted Pope Francis in November 2022.