President Kais Saied has been facing severe criticism from opponents for sacking the government, suspending parliament, and later moving to rule by decree.
Human Rights Watch has warned that Tunisian authorities are using "repressive" laws to snuff out criticism of President Kais Saied.
"Tunisian authorities are prosecuting citizens in both military and civilian courts and jailing them for public criticism of (Saied) and other officials," it said on Thursday.
"Using repressive laws enacted prior to the Tunisian revolution, prosecutors are going after those who criticise Saied."
Saied on July 25 sacked the government, suspended parliament and lifted MPs' immunity, later moving to rule by decree.
Tunisia was the birthplace of the Arab Spring revolts a decade ago, and Saied's actions came after years of political turmoil and an economic slump exacerbated by the coronavirus pandemic.
While some Tunisians welcomed his moves against a corrupt political system, others have called it a coup and warned of a return to authoritarianism.
'Danger to freedom of the press'
Saied's critics include exiled former president Moncef Marzouki, who was sentenced in absentia this week to four years in prison.
Local media said Marzouki was found guilty of "undermining the security of the state from abroad" and of having caused "diplomatic harm".
A Tunisian judge had issued an arrest warrant against Marzouki in November, two weeks after Saied cancelled his diplomatic passport and ordered the judiciary to investigate him.
"To publicly challenge the president and his seizure of special powers is to risk finding yourself in court," said HRW's Eric Goldstein.
"Silencing critics is doubly dangerous at a time when the president is busy concentrating so much power in his own hands."
Political figures and activists have faced trial in military courts over public criticism of Saied.
Earlier this month, the North African country's journalists' union warned of an "imminent danger to freedom of the press, media and expression" since July 25.
It criticised what it described as "a media lockdown and a flagrant violation of journalists' right to access information".