A Tunisian appeals court on Friday handed jail terms of up to 45 years to opposition leaders, businessmen and lawyers, a court document showed, in what critics said was a sign of President Kais Saied's increasingly authoritarian rule.

Forty people were charged in the case of conspiracy to overthrow the president in one of the largest political prosecutions in Tunisia's recent history. Twenty of those charged have fled abroad and were sentenced in absentia.

The sentences ranged from five to 45 years, according to a court document seen by Reuters.

Rights groups, such as Human Rights Watch and Amnesty International, said the case is an escalation of Saied's crackdown on dissent since he seized extraordinary powers in 2021. Critics, journalists and activists have been jailed and independent NGOs suspended.

"This is a judicial farce… There is a clear intent to eliminate political opponents," Mokthar Jmai, a lawyer for the defendants, said on Thursday after the trial.

Authorities say the defendants, who include former officials and the former head of intelligence, Kamel Guizani, tried to destabilise the country and overthrow Saied.

Prominent opposition figures including Ghazi Chaouachi, Issam Chebbi, Jawahar Ben Mbarek and Ridha Belhaj, received jail terms of 20 years, another lawyer for the defendants, Dalila ben Mbarek, said. Politician Noureddine Bhiri was sentenced to ten years in prison.

They have all been in custody since being detained in 2023.

The prominent opposition figure Chaima Issa, was sentenced to 20 years, Nejib Chebbi, the leader of the main National Salvation Front opposition coalition, received 12 years, and Ayachi Hammami got five years.

The three are currently free, but authorities are expected to enforce their arrest.

The maximum sentence was 45 years for businessman Kamel Ltaif, while opposition politician Khyam Turki received a 35-year sentence.

Rights groups say Saied has controlled the judiciary since dissolving parliament in 2021, ruling by decree, dissolving the independent Supreme Judicial Council and sacking dozens of judges in 2022.

Opposition leaders say the prosecution is fabricated and accused the president of carrying out a political purge. They say they plan to unite the fragmented opposition against the democratic setback.

In 2023, Saied said the politicians were "traitors and terrorists" and that judges who would acquit them were their accomplices.