"Freedom, freedom, down with the police state," demonstrators chanted as they marched in Tunis on Saturday, also calling for "a halt to impoverishment" in the North African country.

UGTT chief Noureddine Taboubi called on Saied to embrace "dialogue" and "democratic" ways, slamming the "violent discourse... that is dividing the country".

He accused the president of targeting the powerful union. 

Taboubi also condemned the latest wave of arrests and the imprisonment since February of Anis Kaabi, a top UGTT official for highway workers, who had been detained after a strike by toll barrier employees.

"We will never accept such arrests," Taboubi told the protesters.

Saied has concentrating near-total power in his office since he froze parliament and sacked the government in July 2021. 

Around 20 prominent political figures has been arrested over the past two weeks. 

Last week, Tunisian police arrested National Salvation Front founder Jaouhar bin Mbarak, a prominent critic of Kais Saied, and judicial investigations were opened into several leaders of the Ennahda Movement whose leader, Rashid Al-Ghannouchi, is being investigated on terrorist charges.

The UGTT has around one million members and shared a Nobel Peace Prize in 2015 with three other civil society groups for promoting national dialogue in the country of about 12 million inhabitants. 

On 3 February, it launched a series of protests against the economic situation in the country and “attempts to target union activity”.

The UGTT chief also criticised negotiations between the International Monetary Fund (IMF) and Tunisia, which is seeking a bailout package worth nearly $2 billion from the fund, adding that the union is totally opposed to any lifting of government subsidies on basic goods such as foodstuff and fuel.

The United States earlier on Thursday slammed what it called an "escalating pattern" of arrests in Tunisia of opposition figures, and expressed concern over reports that people who were in contact with US diplomats in Tunis are being targeted.

"We are alarmed by reports of criminal charges against individuals in Tunisia resulting from meetings or conversations with US embassy staff on the ground," State Department spokesman Ned Price told reporters.

Tunisia's foreign ministry reminded diplomats to "not interfere" in the country's internal affairs while President Saied warned the trades union federation against inviting foreigners to their demonstration.

*This story has been edited by Ahram Online