Amira Bouraoui, a key leader of 2019 mass protests that brought down Algeria's president, has escaped to France, sparking a diplomatic row, reports the BBC.
A doctor by training, the journalist and activist was banned from leaving Algeria pending an appeal trial but was not in detention.
The holder of a French passport, she allegedly illegally went to Tunisia and then on to France with diplomatic help.
Algeria has recalled its ambassador to Paris over the affair.
The Algerian foreign ministry accused French diplomats and other personnel of participating "in the illegal and secret evacuation of an Algerian national".
It said the incident was unacceptable and caused great damage to relations between Algeria and France, which had been warming recently after decades of animosity.
Bouraoui had been sentenced in 2021 to two years in jail for "offending Islam" and insulting the president, but was appealing against the ruling. She had spent 11 days in jail when the case was first in court.