Plainclothes security officers in Tunisia detained a prominent critic of President Kais Saied in the early hours of Saturday after a military court ruling, his lawyer told AFP.
Seifeddine Makhlouf had been found guilty of insulting police during a standoff at Tunis airport in March 2021.
Makhlouf, head of Islamist nationalist party Al-Karama, shouted "down with the coup" and "long live Tunisia" before being bundled into a car, according to a Facebook video posted by the lawyer.
Rights groups say military trials of civilians have become increasingly common in Tunisia since a power grab by Saied.
Tunis military appeals court on Friday sentenced Makhlouf to 14 months in prison with immediate effect, his lawyer Ines Harrath told AFP.
A court had initially sentenced him to five months' jail.
"Around 25 officers in plainclothes surrounded his house at 11:00 pm," Harrath said.
After a two-hour standoff, "they came into the house and he left with them".
Makhlouf has been a prominent critic of Saied, who in July 2021 froze parliament and seized far-reaching executive powers in what critics have called a "coup" and an attack on the only democracy to have emerged from the Arab Spring uprisings more than a decade ago.
Saied later took control of the judiciary and pushed through a new constitution giving his office almost unlimited powers.
Makhlouf in March 2021 led a group of Al-Karama MPs to Tunis airport in a bid to force authorities to lift a travel ban against a woman barred from boarding her flight, sparking a standoff that was widely shared online.
The court on Friday also sentenced several other Al-Karama members and a lawyer to shorter prison sentences, but they were not immediately detained.
The head of the National Salvation Front opposition alliance told journalists on Saturday that the rulings reflected "a mentality of vengeance".
"We're seeing the killing of freedoms and the destruction of democracy," Ahmed Nejib Chebbi said.
"There's a desire to decapitate the leadership of the civilian and political opposition."
A statement on the presidency's Facebook late on Friday called for efforts to "tackle all the corrupt and those who believe they are above the law".
Makhlouf also received a year-long suspended prison sentence last February for "attacking the dignity of the army", after losing his parliamentary immunity following Saied's power grab.
He was also banned from working as a lawyer for five years.
A military court upheld the one-year prison sentence in June but his lawyer in that case said he would appeal.
"Putting civilians on trial in military courts is an attack on freedoms," Harrath said. "This case is related to the defendants' positions on Kais Saied."