Tanzania's opposition leader Tundu Lissu was set to appear in court on Thursday to face a charge of treason, which carries a potential death penalty, weeks after his party was disqualified from upcoming elections.
Authorities in the east African nation have increasingly cracked down on the opposition Chadema party ahead of the presidential and parliamentary polls in October.
Chadema accuses President Samia Suluhu Hassan of returning to the repressive tactics of her predecessor John Magufuli.
Amnesty International has called for Lissu's immediate and unconditional release, while his deputy, John Heche, who was also briefly detained this week, has urged protests.
Lissu, 57, was due at a court in Tanzania's business capital, Dar es Salaam, early Thursday.
He has not been seen since a brief court appearance on April 10 when he was charged with treason, which has no option of bail, and "publication of false information".
At the time, a defiant Lissu told supporters: "The treason case is a path to liberation."
He has been arrested several times in the past, but this is the first time he has faced such a serious offence.
The pugnacious leader has led a forceful charge against the government, promising that his party would not participate in polls without significant electoral reforms.
Chadema's refusal to sign an electoral "code of conduct" prompted its disqualification, but the party has said the rules were designed to "ensure that the ruling party remains in power" and that its ban was unconstitutional.
Optimism denied
The president's party, Chama Cha Mapinduzi (CCM), won an overwhelming victory in local elections last year but Chadema says the vote was not free or fair since many of its candidates were arbitrarily disqualified.
Chadema has demanded voting reforms, including a more independent Electoral Commission and clearer rules to ensure candidates are not removed from ballots.
Lissu warned last year that Chadema would "block the elections through confrontation" unless the system was improved.
The opposition's demands have been long ignored by the ruling party.
A lawyer by training, Lissu entered parliament in 2010 and ran for president in 2020.
He was shot 16 times in a 2017 attack that he believes was ordered by his political opponents.
After losing the 2020 election to Magufuli, he fled the country but returned in 2023 on a wave of optimism as Hassan moved to relax some of her predecessor's restrictions on the opposition and the media.
Those hopes proved short-lived, with rights groups and Western governments increasingly critical of renewed repression, including the arrests of Chadema politicians as well as abductions and murders of opposition figures.
In a statement following the detention of Lissu, Amnesty described a "campaign of repression" by authorities, criticising the "heavy-handed tactics to silence critics".
© Agence France-Presse
