Police locked down a large area of central Tunis on Saturday, blocking roads to prevent a major protest backed by the country's powerful labour union, prompting angry criticism from members of parliament, reports Reuters.
Large numbers were expected to rally to mark the 2013 killing of a prominent activist and to protest against police abuses that they say have imperilled the freedoms won in the 2011 revolution that triggered the "Arab spring".
Riot police deployed cordons around the city centre, stopping both cars and many people from entering the streets around Avenue Habib Bourguiba as hundreds of people began to gather, a Reuters witness said.
Unlike previous marches in the wave of street protests that have rippled across Tunisia in recent weeks, Saturday's rally is backed by the UGTT union, the country's most powerful political organisation with a million members.
Protests, which began with clashes and rioting in deprived districts last month over inequality, have increasingly focused on the large number of arrests, and reports – denied by the Interior Ministry – of abuse of detainees.
Mohammed Ammar, a member of parliament for the Attayar party, said he had phoned the prime minister to protest against the closure of central Tunis to the protest.
A decade after Tunisia's revolution, its democratic political system is in crisis, mired in endless squabbling between the president, prime minister and parliament while the economy stagnates.
While some Tunisians, disillusioned by the fruits of their uprising, have sung nostalgia for the better living conditions they remember from the days of autocracy, others have decried a perceived erosion of the freedoms that democracy secured.
The febrile climate has for some recalled the political polarisation after a hardline militants assassinated secular activist and lawyer Chokri Belaid in February 2013.
His death triggered a wave of mass protests in Tunisia that led to a grand bargain between the main Islamist and secular political parties to stop the country sinking into violence