CAIRO (AP) — Dozens of detainees in Yemen have been transferred from two secret facilities to government-run prisons in the southern cities of Mukalla and Aden, a senior Yemeni official, activists, and families of prisoners said Monday.

A group of 133 detainees was transferred to the newly-renovated Central Prison in Mukalla from the Riyan airport, a senior Yemeni security official said. The airport was one of 18 secret prisons that an Associated Press investigation revealed as run by the United Arab Emirates or its allies, where former prisoners said torture was widespread.

The UAE denies the allegations and says all prisons in government-controlled territory are run by Yemeni authorities.

The official says there are no more prisoners in Riyan and that the airport will reopen soon. He spoke on condition of anonymity because he wasn't authorized to speak to reporters. Families of two detainees also said their sons were moved to the new prison.

Families of detainees, former prisoners and mediators had said Riyan airport and other secret sites in Mukalla held hundreds of detainees. It's not clear whether the rest of the prisoners have been transferred to other facilities or released.

In Aden, Yemeni and UAE officials inaugurated a newly built prison near the site of another secret prison.

According to a rights advocate, who spoke on condition of anonymity for fear of repercussions, said dozens of prisoners were hastily moved from the secret facility to the new prison overnight, without being given time to gather their belongings. They were issued blue prison uniforms at the new facility.

Pictures posted on a number of Aden news portals showed a new clinic, offices, and a dining hall inside the new prison. A handful of prisoners in blue prison suits appeared in a picture sitting on a wooden bench while eating from plastic bags.

In recent weeks, prisoners at the secret facility had started a hunger strike to protest the conditions of their detention and smuggled statements out to media outlets calling on rights groups to intervene. Some were taken to hospitals because of their deteriorating health.

Aden is the headquarters of government forces who have been battling the country's Shiite rebels, known as Houthis, since 2015. The government forces are allied with a Saudi-led coalition that includes the UAE and is supported by the United States.

Aden is still home to a number of secret prisons, some located in former night clubs and hotels, according to rights groups.