The daughter of Rached Ghannouchi, Tunisia's former house speaker and leader of the main opposition party Ennahda, on Wednesday filed a petition requesting the immediate release of her father.
Yusra Ghannouchi joined family members of five detained Tunisian opposition figures who also made the request for their relatives' release to the African Court of Human and Peoples' Rights.
“We are going to exhaust every single option that we have to seek justice and of course we are continuing with the cases in Tunisia,” Ms Ghannouchi told The National.
She said President Kais Saied "cannot pretend that Tunisia is living in isolation".
Turning to the African legal body highlights a lack of trust in the independence of the Tunisian judicial system, where national judges are subjected to regular threats and pressure from authorities, she claimed.
“We see a near breakdown of the rule of law in Tunisia and very little respect for legal proceedings but we will continue to seek justice there too,” she said.
"We need to make sure that there is no impunity and that there should be consequences for such violations."
Mr Ghannouchi, 81, is the highest-profile figure to be arrested in Tunisia as Mr Saied tightens his grip on power.
More than 20 opposition figures have been arrested in Tunisia in recent weeks, including members of the National Salvation Front and Ennahda.
According to a press release by the families, the petition is requesting that the court pushes the Tunisian government to release the prisoners.
Ennahdha member Said Ferjeni, former terrorism prosecutor Bachir Akermi and The Democratic Current party leader Ghazi Chaouachi are among those detained.
Family members of Ridha Bouzayene, a supporter of Ennahdha party who died during an opposition rally last year, are requesting an investigation into his death through the same petition.
Kaouther Ferjani, daughter of prisoner Said Ferjani, told The National from Arusha, Tanzania, where she flew to file the petition, that they regarded the court as "a neutral party that could look at the case”.
Ms Ferjani said she was hopeful the petition would push for more action from the union.
Tunisia is one of only six African countries fully signed up to the court’s charter.
Tunisian citizens can therefore directly file complaints against the state to the court.
"Its decisions are binding so we are asking the court to look at the case since we know that there are violations of the African charter," said Ms Ghannouchi.