Tunisian media mogul and former presidential candidate Nabil Karoui has been hospitalised three days after launching a hunger strike protesting his continued pre-trial detention, a justice official said Tuesday.

"The doctor asked that Mr. Karoui be transferred to hospital because of his state of health," judicial official Mohsen Dali told AFP.

Karoui, 57, leader of the liberal Qalb Tounes party, was taken to hospital on Monday night, after beginning his hunger strike on Saturday, and remains in hospital for tests.

Karoui's party says he has been held "illegally" since May 5, the end of the maximum six-month period of pre-trial detention allowed in the North African nation.

A judge can intervene to extend that period, but the suspect has a right to appeal.

Karoui is a business and media mogul whose party came second in October 2019 parliamentary elections and allied itself with the Islamist-inspired Ennahdha party.

President Kais Saied has accused the two parties of corruption.

During Karoui's presidential election campaign that same year, he spent more than a month in prison over money laundering and tax evasion charges stemming from a 2017 investigation.

He was arrested again in December 2020 over the same affair.

Karoui is the founder of private channel Nessma TV, partly owned by former Italian prime minister Silvio Berlusconi.