A French student researching the career paths of 2011 protesters in Tunisia has been held in the North African country since October 19 after a military judge ordered his detention, his supervisor said on Thursday, October 31.

Vincent Dupont, a 27-year-old doctoral student, had been in Tunisia for around 10 days conducting research interviews, Vincent Geisser, director of the Institute for Research and Studies on the Arab and Muslim Worlds at France's Aix-Marseille University, told Agence France-Presse (AFP).

"He was detained by Tunisian police on Saturday, October 19, taken to an interrogation center, placed in custody, and the same day brought before a military judge," he said, calling the last measure "exceptional" for a French student.

Dupont hoped his interviews would provide material for a paper on the social and career paths of "people who might have been active during the 2011 revolution" that toppled longtime dictator Zine El Abidine Ben Ali, Geisser said. "It is not a political topic linked to dissidents or opponents or a security topic, but a typical sociology topic," he added, calling for his student to be released.

Geisser said French diplomatic services were following Dupont's case and that his family has been in Tunisia since the beginning of this week.

Tunisia's President Kais Saied was re-elected with more than 90% of votes earlier this month, three years after he made a sweeping power grab in the country.

The United Nations has said it was troubled by a presidential election campaign that had been "marred by a crackdown on the opposition, independent activists and journalists." Rights groups fear Saied's re-election will tighten his grip on the only democracy to emerge from the 2011 Arab Spring protests.