The Hirak protest movement started in 2019, when hundreds of thousands poured onto the streets against longtime president Abdelaziz Bouteflika's bid for a fifth term.
The protests continued after his ouster, with demonstrators demanding a sweeping overhaul of the ruling system in place since Algeria's 1962 independence from France.
In a report based on testimonies of detainees, families and lawyers, Amnesty said Algerian authorities had "escalated their repression of peaceful dissent" since the movement ended in early 2020 due to the Covid pandemic and a ban on protests.
The London-based human rights group said hundreds of people had been arbitrarily arrested and detained and that dozens of peaceful protesters, journalists and activists still languished behind bars.
"It is a tragedy that five years after brave Algerians took to the streets in their masses to demand political change and reforms, the authorities have continued to wage a chilling campaign of repression," said Heba Morayef, Amnesty's regional director for the Middle East and North Africa.
"Algeria's authorities must immediately and unconditionally release all those detained solely for exercising their rights to freedom of expression, peaceful assembly, and association," she said in a statement.
"They must ensure that human rights defenders, journalists, activists, trade unionists and others are able to exercise their rights and freely express critical views without fear of reprisals."
Amnesty said the Algerian authorities had intensified their crackdown on dissent since 2021, arresting dozens of people including journalists, human rights defenders and whistleblowers.
They included independent journalist Ihsane El Kadi, who in October lost two appeals against a seven-year jail sentence "on charges related to his journalism," it said.
Algeria ranks 136 out of 180 countries and territories in the Reporters Without Borders World Press Freedom Index.
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