PARIS  — An Algerian appeals court has upheld a five-year prison sentence against French-Algerian writer Boualem Sansal, according to his supporters.

Sansal, a vocal critic of the Algerian regime, has been behind bars since being arrested as he stepped off a plane in Algiers in November. He was convicted in March for undermining national unity.

“The situation that has been imposed on Boualem Sansal is unbearable for all the French and for this government,” French Prime Minister François Bayrou said Tuesday.

The 80-year-old author’s detention sparked outrage across the literary world. Algeria has been accused of conducting hostage diplomacy with Sansal, who is suffering from cancer, as the country’s relationship with its former colonizer has soured since France recognized Morocco’s sovereignty over the disputed territory of Western Sahara last summer.

French President Emmanuel Macron has called for Sansal’s release several times, and in January said Algeria had “dishonor[ed] itself” by keeping him in prison.

Sansal’s main support group says the novelist — who in 2015 was awarded one of France’s most prestigious literary prizes, the Grand prix du roman de l’Académie Française — has been in and out of hospital since he was imprisoned. His fate now rests in the hands of Algerian President Abdelmadjid Tebboune, who is reportedly considering pardoning Sansal on Algeria’s independence day on Saturday.

“We are outraged by this verdict. [The Algerian government] is playing with us. We are now hoping for a presidential pardon, we have no other solution,” said Noëlle Lenoir, a former government minister and head of Sansal’s support group.

Sansal’s verdict comes on the heels of an Algerian court sentencing Christophe Gleizes, a French football journalist, to seven years in prison on charges of advocating terrorism. One of Gleizes’ employers, “So Foot,” said the freelance reporter was innocent and had been “locked up for doing his job.”

Victor Goury-Laffont contributed to this report.