A Tunisian court has sentenced a lawmaker to eight months in prison over social media posts mocking President Kais Saied following recent deadly floods.

Ahmed Saidani was arrested earlier this month after he posted on social media about Saied's visits to flood-hit areas, calling him the "supreme commander of sanitation and rainwater drainage".

He was jailed on Thursday on charges of insulting others via communication networks, a judicial official said.

Saidani's lawyer, Houssem Eddine Ben Attia, told AFP news agency that his client was being prosecuted under a telecommunications law against "harming others via social media", an offence punishable by up to two years in prison.

Human rights groups have criticised what they describe as an escalation of Saied's crackdown on dissent since he suspended Tunisia's parliament in 2021 and began ruling by decree.

Saidani, once a supporter of Saied's consolidation of power and the arrest of opposition figures, has recently turned into an outspoken critic of the president.

In his Facebook post, the lawmaker mocked the president for "taking up the hobby of taking photos with the poor and destitute" while visiting flooded areas in the capital, Tunis and other parts of the country.

Saidani, who was elected as a lawmaker in 2022, has also accused the president of monopolising decision-making while avoiding responsibility, leaving others to take the blame.

"This is a violation of the law and an attack on institutions. How can parliament hold the executive authority to account if it carries out an unlawful arrest over critical views," fellow MP Bilel Mechri told Reuters news agency.

At least five people died and several remain missing after Tunisia experienced its heaviest rainfall in over 70 years last month.

President Saied was elected in 2019 promising a return to stable government following years of political instability after long-time leader Zine al-Abidine Ben Ali was ousted by the "Arab Spring" street protests in 2011.

His critics accuse him of reimposing aspects of authoritarian rule and curtailing political freedoms.

Last November, a Tunisian court handed jail terms to dozens of opposition leaders, lawyers and businessmen accused of attempting to overthrow the president.

The 67-year old leader rejects claims of dictatorship, insisting he is upholding the law and working to "cleanse" the country.

Tunisian lawmakers have parliamentary immunity, protecting them from arrest while performing their official duties, though they can be detained for committing a criminal offence.