Amnesty International on Monday urged authorities in Tunisia to stop using "largely outdated, overly broad and repressive laws" to crack down on freedom of expression online.
Freedom of speech is seen as one of the most solid achievements of the North African nation's 2011 revolution that ousted longtime president Zine El Abidine Ben Ali.
The UK-based rights group said that since 2018, at least 40 people have faced criminal prosecution for "publishing online posts critical of local authorities, the police or other state officials".
It said those targeted included "bloggers, administrators of widely followed Facebook pages, political activists and human rights defenders".
Amnesty charged that while most of the cases failed to lead to prison sentences, the legal proceedings amounted to "harassment and intimidation" and would have "a chilling effect".
"It is extremely disturbing to see bloggers and activists being targeted with criminal prosecutions under laws that date back to the time of repression in Tunisia 10 years after the revolution," said Amna Guellali, Amnesty's deputy regional director for the Middle East and North Africa.
"These prosecutions threaten the human rights progress made so far in Tunisia where the right to freedom of expression is a hard-won value of the revolution," she said in a statement.
Tunisia is seen as a rare democratic success story of the Arab Spring uprisings that broke out almost a decade ago.
The rights group also released a report Monday and charged that Tunisia's interior ministry "openly threatens to prosecute people for legitimate criticism of police conduct".
It also cited a "steady increase of prosecutions for Facebook posts that reveal cases of alleged corruption, criticise the authorities, or are deemed to 'insult' officials online".
Amnesty urged Tunisian authorities to prioritise the reform of "largely outdated and overly broad laws that allow repression" and to cease all action against individuals peacefully exercising their right to freedom of expression.