Tanzanian police have arrested an opposition leader accused of inciting anti-government demos.
The leader of Chadema Women’s Wing for Kisutu, Ms Elizabeth Mambosho, was locked up on Thursday.
Kinondoni Regional Police Commande Muliro Jumanne said were holding Ms Mambosho for interrogation.
Police accuse Ms Mambosho of using her social media accounts to incite Chadema supporters to take to the streets.
The arrest came as Tanzanian police beefed up security in most towns over the demos slated for Thursday.
In the capital, Dar es Salaam, the central business district was calm for the better part of Thursday morning as police vehicles patrolled streets.
The situation was the same at Kariakoo as traders went about their businesses.
Calm was also witnessed in most parts of Zanzibar, whose union with Tanganyika to form the United Republic of Tanzania is being marked today.
In Dodoma, where the 54th anniversary of Union Day celebrations are being held, it was generally calm but with heavy police presence.
The scheduled demos were organised mostly via social media platforms.
But while calm prevailed, most town centres were deserted as offices and some businesses remained closed.
Police on Wednesday threatened a robust response to any demonstrations against President John Magufuli.
A protest in February led to the death of a student hit by a stray bullet.