Chad's President Mahamat Idriss Deby and France's President Emmanuel Macron after a bilateral meeting at the Africa Forward summit in Nairobi on May 12, 2026. [AFP]

Chadian opposition leader Succes Masra will remain in jail after the supreme court rejected his appeal on Thursday, one of his lawyers told AFP.

Masra, a former prime minister and a leading opponent of President Mahamat Idriss Deby Itno, was arrested in May 2025.

In August 2025, he was sentenced to 20 years in prison for inciting violence and complicity to murder in what Human Rights Watch called a politically motivated trial.

"Despite all the legal arguments we presented before the higher court, it chose to reject the appeal," his lawyer Francis Kadjilembaye said after the hearing.

The ruling upholds the conviction handed down last August.

HRW said last week that his continued detention on these charges showed the "government's intolerance of dissent".

Security was tight around the Supreme Court in the capital, N'Djamena, with police deployed in large numbers and several journalists denied access to the hearing, according to an AFP reporter.

The decision comes amid heightened political tensions in Chad, where eight opposition leaders were sentenced earlier this month to eight years on charges including insurrection.

They belonged to the main opposition coalition, which was dissolved by authorities days earlier.

Opposition groups have repeatedly complained of intimidation and bans on public gatherings.

In late April, a member of Masra's party, The Transformers, was shot dead by police during a protest demanding his release.

Trained as an economist in France and Cameroon, Masra had been a fierce opponent of the ruling authorities before they named him prime minister five months ahead of the 2024 presidential election.

Masra faced off against Deby in the 2024 presidential elections, winning 18.5 percent against Deby's 61.3 percent, but claimed victory.