Tunisian politicians and social media users called Monday for transparency on President Beji Caid Essebsi's health after he was hospitalised last week with a "serious illness".
It came as a spokeswoman for the presidency said there was a "marked improvement" in the health of 92-year-old Essebsi, who was taken to hospital on Thursday.
"As soon as the doctors decide he will leave hospital," spokeswoman Saida Garrache told private radio station Mosaique FM without giving details, saying it was up to the hospital to provide further information.
Tunisians are concerned that the cradle of the Arab Spring uprisings could descend into political instability in case of a prolonged vacancy of the presidency.
A group of unidentified Tunisians posted online a statement with the hashtag "#we have the right to know", demanding "transparency" concerning Essebsi's health.
According to them, rumours which have spread on media outlets have "disrupted state institutions".
Several politicians, including members of parliament and party leaders, have also demanded online that the authorities provide details on the president's condition.
Essebsi was taken to the military hospital in Tunis for a "serious illness", his office said at the time, the same day that twin suicide attacks claimed by the Islamic State group killed a police officer and wounded several other people.
After his hospitalisation, another key advisor Firas Guefrech described the president's condition as "critical", and in a later tweet said Essebsi was "stable".
The president's son, Hafedh Caid Essebsi, spoke late Thursday after visiting his father in hospital of "the beginnings of an improvement" in his condition.
The country's first democratically elected president, Essebsi came to power in 2014, three years after the Arab Spring that sparked revolts and regime changes in several countries in the region.