The Tunisian journalists' union accused authorities on Tuesday of trying to "intimidate the media", after a minister sued a news outlet for "defaming" the prime minister.
The Business News website had published an editorial last week under the title "Najla Bouden, the gentle woman", reviewing the premier's 13 months in office under President Kais Saied.
Since starting the job in October 2021, Bouden had "achieved nothing", the article claimed, accusing the government of "continuing to put sticks in the the wheels of Tunisia's economy".
Bouden was appointed by Saied in the wake of a July 2021 power grab that has sparked fears for democracy in the birthplace of the Arab Spring uprisings.
Saied has since issued a string of presidential decrees seen as repressive by rights groups, including one in September restricting press freedom.
On Friday, justice minister Leila Jaffel filed a complaint against Business News for defamation, "false allegations against a public official" and "contempt of the head of government".
The justice ministry declined to give AFP any further details on the case.
On Monday, Business News director Nizar Bahloul was questioned by police in Tunis, he told AFP, saying they had asked about the article and the expressions it used.
The vice president of the SNJT journalists' union, Amira Mohamed, said Tuesday the column contained "no defamation".
"The move to press charges shows that the authorities want to intimidate the media and journalists in order to silence them," she told AFP.
"We condemn this kind of repressive practice, under a draconian text."
Business News would be the first media outlet to be prosecuted under the September 16 decree.
The law allows courts to issue heavy fines and jail terms of up to five years against anyone "who deliberately uses communication networks and information systems to produce, promote, publish or send false information or false rumours".
Those penalties can be doubled when the publications are about state officials.