A new Tunisian constitution greatly expanding presidential powers easily passed a referendum on Monday, according to an exit poll, but with very low turnout.

President Kais Saied ousted the parliament last year and moved to rule by decree, saying the country needed saving from years of paralysis. He rewrote the constitution last month.

Opposition parties boycotted the referendum, saying it dismantles the democracy Tunisia introduced after its 2011 revolution and could start a slide back toward autocracy.

Tunisia, meanwhile, faces a looming economic crisis and is seeking an International Monetary Fund (IMF) rescue package, issues that have preoccupied ordinary people far more over the past year than the political crisis.

The exit poll by Sigma Conseil said 92.3% of the eligible voters who took part in the referendum supported Saied's new constitution. There was no minimum level of participation. The electoral commission put preliminary turnout figures at 27.5%.

The new constitution gives the president power over both the government and judiciary while removing checks on his authority and weakening the parliament.

His opponents say his moves last year constituted a coup and have rejected his unilateral moves to rewrite the constitution and put it to a referendum as illegal.

However, his initial moves against the parliament appeared hugely popular with Tunisians, as thousands flooded the streets to support him, but with little progress in addressing dire economic problems, that support may have waned.

Official turnout figures for the referendum will be closely watched and the electoral commission is expected to release its own preliminary number later.

The lowest turnout of any national election since the 2011 revolution, which triggered the Arab Spring, was 41% in 2019 for the parliament that Saied has dissolved.

The president's opponents have also questioned the integrity of a vote conducted by an electoral commission whose board Saied replaced this year, and with fewer independent observers than for previous Tunisian elections.

Casting his own vote on Monday, Saied hailed the referendum as the foundation of a new republic.

Western democracies that looked to Tunisia as the only success story of the Arab Spring have yet to comment on the proposed new constitution, although they have urged Tunis over the past year to return to the democratic path.

"I'm frustrated by all of them. I'd rather enjoy this hot day than go and vote," said Samia, a woman sitting with her husband and teenage son on the beach at La Marsa near Tunis.

Others voiced support for Saied.

Casting his vote on Rue Marseilles in downtown Tunis, Illyes Moujahed said former law professor Saied was the only hope.

"I'm here to save Tunisia from collapse. To save it from years of corruption and failure," said Moujahed, first in line.

But the atmosphere was muted in the run-up to the referendum, with only small crowds attending rallies for and against the constitution.

Economic decline since 2011 has left many Tunisians angry at the parties that have governed since the revolution and disillusioned with the political system they ran.

To address economic privations, the government hopes to secure a $4 billion loan from the IMF, but faces stiff union opposition to the required reforms, including cuts to fuel and food subsidies.