Habib Essid is currently in intensive care in a hospital in Tunis, according to his entourage.
The 71-year-old led a coalition government in 2015-16 and no longer has political responsibilities.
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He was invited on Friday evening on the Paris-Tunis program, in partnership between France 24 and the Tunisian public television channel Wataniya.
The former prime minister was answering journalists' questions live from the Bardo Palace in Tunis when he had speech problems and lost control in one hand.
The program was quickly interrupted, and Mr. Essid was evacuated to the military hospital in Tunis, where he is still in intensive care, told AFP a relative and an official of the Wataniya channel.
The current Prime Minister Hichem Mechichi went to his bedside Saturday morning, said the services of the head of government, without giving details on his state of health.