The families of detained Tunisian pro-migrant and anti-racism activists, imprisoned since May, launched an appeal on Tuesday for their release.
Romdhane Ben Amor, the head of FTDES, an NGO, said the 10 detainees' organisations "were engaged in humanitarian work, not political advocacy".
The authorities, however, "criminalised their actions", he said at a press conference.
The aim, Ben Amor said, was to "further weaken migrants and refugees and to push them to accept 'voluntary returns' organised by the (UN's) International Organization for Migration".
Tunisia is a major transit country for African migrants hoping to cross the Mediterranean to Europe in search of economic opportunities and a better life.
In 2023, Tunisian president Kais Saied denounced what he called "hordes of sub-Saharan migrants" who threatened to "change the country's demographic composition".
That was followed by a crackdown on migrants and last year's arrest of activists.
Among those at the press conference was Emna Riahi, the mother of Sherifa Riahi, the former head of Terre d'Asile Tunisie.
She demanded that her daughter, a parent of two young children, be released and have a trial after charges against her of money laundering and terrorism were dropped.
Also present were the daughters of Mustapha Djemali, the 80-year-old founder of the Tunisian Council for Refugees and former North Africa chief for the UN's refugee agency.
Yusra and Emna Djemali said their father had lost 35 kilogrammes (77 pounds) while in prison and had been denied medication "for four or five months".
All these activists "are imprisoned to make it seem as though the president's racist rhetoric was based on real facts," said Ben Amor, lamenting what he called the "complicit silence" of the European Union and international organisations.