Tunisian authorities on Friday detained presidential candidate Nabil Karoui on charges of tax evasion and money laundering.
The media mogul is a key contender the presidential poll schedule for September 15.
Earlier Friday, Karoui's Nessma TV and two other broadcasters were banned by electoral and media authorities for not holding licenses and influencing government bodies.
Karoui was charged in early July with money laundering. He claims there are "attempts to undermine his growing popularity."
Tunisia is holding a presidential election after the death last month of Beji Caid Essebsi, the first democratically elected president following the popular uprising in 2011 that ousted dictator Zine El Abidine Ben Ali.
Tunisian Prime Minister Youssef Chahed and Abdelfattah Mourou of the Islamist inspired Ennahdha party are other top candidates in the race.