Tanzania's opposition Chadema party on Monday said its leader Freeman Mbowe had been arrested, the latest of several politicians to have been detained.

Police are also said to have rounded up several hundred youth supporters, saying they expect a scheduled demonstration marking International Youth Day to turn violent. The detentions come amid fears of a backslide in President Samia Suluhu Hassan's moves away from authoritarian rule.

What has happened to the arrested leaders?

Mbowe was said to have been arrested as he visited the southwestern city of Mbeya to meet police and army leaders.

Chadema said he was arrested at the city's Songwe airport alongside John Pambalu, the chairman of the party's youth wing Bavicha.

Mbowe had planned to use the visit to inquire about the health and whereabouts of already-detained opposition figures, including former presidential candidate Tundu Lissu.

Mbowe had on Sunday demanded "the immediate and unconditional release of all our leaders, members, and supporters who were arrested in various parts of the country."

"The party is closely monitoring the situation and will continue to inform the public of every development step by step," he said.

Hassan took over as president in 2021 after the sudden death of her predecessor John Magufuli. Since then, she has departed from the late president's authoritarian policies, relaxing some media and opposition restrictions.

However, opposition parties and rights groups have also criticized her for arrests last DWyear of people planning protests against a port management deal.

Mbowe was previously detained for about seven months after he and other Chadema leaders were arrested before a public forum to demand constitutional reforms. He was released in March 2022.

Lissu, Chadema's deputy chairman and a fierce critic of Hassan's ruling center-left Chama Cha Mapinduzi (CCM), returned to Tanzania soon after Hassan lifted a ban on opposition rallies that was imposed in 2016. Lissu had previously spent five years mainly living in exile after an assassination attempt in 2017.

The country is due to hold presidential and parliamentary polls late next year, with Lissu expected to run for the presidency once again. DW