In a statement, the High Commissioner for Human Rights said that she had been disturbed by reports of continued intimidation and harassment against leaders and members of the opposition.
She also called for the immediate release of those detained for exercising their human rights.
“The tense situation in the country will not be defused by silencing those who challenge the outcome of the elections, but rather through a participatory dialogue”, Ms. Bachelet said, before urging the Tanzanian authorities “to respect and facilitate exercise of the rights to freedom of expression and of peaceful assembly”.
Ms. Bachelet highlighted reports that following vote-casting in the east African nation last month, at least 150 opposition leaders and members had been arrested in mainland Tanzania and Zanzibar.
While most have been subsequently released, at least 18 reportedly remain in custody, the UN rights chief said.
Peaceful opposition call
Her comments come after the country’s main opposition parties called for peaceful demonstrations and fresh elections, after President John Magufuli was returned to office last month with more than 80 per cent of ballots cast.
According to the UN High Commissioner for Human Rights, the authorities said that those arrested had been planning violent protests.
Ms. Bachelet also noted that ahead of the arrests, police officials announced that they would not allow protests to go ahead. They cited allegation of “plans to cause chaos”, the High Commissioner said, adding that they threatened to use force and detain anyone taking part in demonstrations.
Under international law, there is a presumption in favour of considering assemblies to be peaceful, the High Commissioner stressed.
She called on the Government of Tanzania to ensure that security forces and law enforcement officials act according to the rule of law and human rights norms and standards.
The developments follow reported pre-election intimidation and harassment of civil society organisations and journalists, as well as allegations of police brutality against opposition members and their supporters on the day of the election.
Ms. Bachelet also called for prompt, thorough, independent and impartial investigations into all allegations of human rights violations before, during and after the polls.
In particular, she urged action to investigate the killing of at least 10 people and the injuries sustained by more than 50 others in Zanzibar on 26 October – two days before the vote.
The High Commissioner also expressed concern at internet restrictions – including the blocking of social media and messaging platforms – and the censoring of election-related content.
“Free flow of information is critical to any democratic society, and especially so in an electoral context,” the High Commissioner said, adding that any restrictions on information and communication technology must be in line with international human rights laws and standards.