Tanzanian police said Friday they were banning the main opposition party from holding a protest against killings and abductions of its members.
The Chadema party had called a mass rally in the commercial capital Dar es Salaam on September 23 unless recent disappearances were investigated and missing members "brought back alive or dead".
But police spokesperson David Misime told reporters that "the Chadema protests are banned" and warned the party that "police will deal with anyone who violates this order".
There had been hopes Tanzania was entering a period of democratic freedom under President Samia Suluhu Hassan after she reversed restrictions on opposition parties and the media by her predecessor John Magufuli.
But recent crackdowns, including the mass arrest of Chadema leaders and supporters ahead of a planned rally last month, have raised fears of renewed repression.
Chadema accuses the authorities of "killings and abductions", including of Ali Mohamed Kibao, a member of its national secretariat, who was found dead at the weekend after being beaten and doused with acid, according to the party.
Chadema spokesman John Mrema told AFP the party would proceed with the protest.
"The police spokesperson is not authorised to ban protests," he said. "It seems the police are worried because they are also suspects."
Emmanuel Nchimbi, secretary general of the ruling Chama Cha Mapinduzi (Revolution Party), blamed the abductions on "a gang" and urged Chadema not to protest.
"The killers want to divide us as a nation... Chadema should not fall into the trap," he said.
The Tanganyika Law Society said last month that 83 people were either kidnapped or went missing between 2016 and 2024.
The US embassy in Tanzania has called on the authorities to conduct an "independent, transparent, and prompt investigation" into Kibao's death.