ACT-Wazalendo party leader Zitto Kabwe was visiting local councils in Morogoro, in eastern Tanzania, where his party members had won elections.
Mr Kabwe was released Friday morning on $22,000 police bail.
Tanzanian outspoken opposition leader Zitto Kabwe spent Thursday night behind the bars after he was arrested for holding a political gathering without a permit.
The ACT-Wazalendo party leader was visiting local councils in Morogoro, in eastern Tanzania, where his party members had won elections.
“I am being escorted to Mgeta police station in Mvomero district, Morogoro," Mr Kabwe tweeted on Thursday evening, adding that: “No reason has been given for the arrest.”
Tanzania banned political rallies soon after the October 2015 election when President John Magufuli declared time for politicking was over.
Since then several opposition leaders have been arrested for illegal assembly.
Mr Kabwe has himself been taken to custody several times including last October when he was accused of breaching the Cyber Crime Act and the Statistics Act by questioning economic data provided by the central bank saying the figures had been manipulated.
“We shall not be deterred from demands for democracy and civic rights by harassments, intimidation and arbitrary use of repressive laws. We shall not succumb to stints in their police cells. Our struggle for a Democratic Tanzania must continue,” Mr Kabwe said on Thursday.
He was released Friday morning on Tsh50 million ($22,000) police bail and