Tunisian judicial authorities on Monday ordered that prominent journalist Zeid El-Heni should be detained and tried on charges of defamation, days after he criticized the trade minister, his lawyer said.

El-Heni will have his first court hearing on January 10 on the charge of "defaming others on social media," his lawyer Ayachi Hammami told reporters.

Police first arrested him on Thursday after he made comments about the minister on local radio in an interview that was posted on Facebook, Tunisia's state news agency said.

Tunisia's journalists union demanded his immediate release, calling his detention a "violation of legal provisions governing the trial of reporters."

Freedom of speech and media were key gains for Tunisians after the 2011 revolution that ousted autocratic President Zine El Abidine Ben Ali and triggered the "Arab Spring" protests.

But activists and journalists say freedom of speech has been deteriorating since President Kais Saied seized wide powers in 2021. Saied has said his actions were needed to save Tunisia from chaos under what he calls a corrupt elite.