Rached Ghannouchi, the leader of the Islamic Ennahdha party - and one of the main opponents of President Kais Saied - appeared before the counter-terrorism court in Tunis on Tuesday.
He was charged with incitement after allegedly referring to the police as "tyrants."
The Ennahdha party, which was the largest in parliament before President Saied dissolved it, said a complaint was filed against him by a police union. It comes in the wake of a series of arrests carried out in political circles since the beginning of February.
At the beginning of 2022, at the funeral of a senior Ennahdha member, Mr. Ghannouchi had said that the deceased "did not fear leaders or tyrants."
These comments were interpreted by the police union as inciting Tunisians to kill each other.
After hearing the case, the judge decided to release Mr. Ghannouchi, his lawyer Sami Triki told AFP.
However, he must now appear before the police research and investigation brigade on Thursday in another investigation. It was opened after a police officer claimed to be in possession of a telephone recording that allegedly compromises him.
"These are trumped-up trials," Ghannouchi said on his arrival at the anti-terrorism court, accusing the power of "instrumentalising justice."
The authorities are trying to "hide Tunisia's real problems," he added.
Ahmed Néjib Chebbi, president of the main opposition coalition, the National Salvation Front, denounced the "judicial harassment" of Mr. Ghannouchi.
"It is a short-sighted policy in the face of economic and social failures and in the face of the international isolation of power," he told AFP, adding that "repression has never stopped the torrent of freedom."
Mr. Ghannouchi had already been before the counter-terrorism court in November 2022 in a case linked to the departure of jihadists in Syria and Iraq.
And in July he was questioned on suspicion of corruption and money laundering linked to transfers from abroad to a charity affiliated with Ennahdha.
At least ten figures - mostly opponents belonging to the Ennahdha movement and its allies, but also the influential businessman Kamel Eltaïef and the director of the private radio station Mosaïque FM, Noureddine Boutar - have been arrested since the beginning of February.
The human rights group Amnesty International described the wave of arrests as "a deliberate attempt to stifle dissent, in particular criticism of the president", and urged President Saied to "end this witch hunt motivated by political considerations."
On Tuesday, the president of the national union of Tunisian journalists Mahdi Jlassi, announced that he has been accused, along with a group of human rights activists, of "insulting the police" on the sidelines of a demonstration in July.
In July 2021, President Saied revised Tunisia's constitution to establish a more presidential system that diminishes the power of parliament.