Algerian police in riot gear used batons on Saturday to break up a crowd of about 50 opposition supporters trying to take part in a protest march inspired by uprisings elsewhere in the Arab world.
A Reuters reporter at the scene said the crowd, chanting "Algeria -- free and democratic!", were dispersed by police about two blocks from May 1 Square, where the anti-government protest was scheduled to start at 11:00 a.m. (1000 GMT).
Large numbers of police were mobilised to try to prevent Saturday's protest from going ahead. Dozens of police vans and military-style police armoured vehicles were dotted around the capital hours before the demonstration was supposed to begin.
The protesters split into two groups in a courtyard of a residential block, where they were surrounded by about 400 police in helmets and body protection.
A coalition of human rights groups, some trade unionists and a small opposition party are calling for weekly protest marches through the capital. The authorities have refused permission for the marches, citing public order concerns.
Unrest in Algeria could have implications for the world economy since it is a major oil and gas exporter, but analysts say an Egypt-style revolt is unlikely because the government can use its energy wealth to placate most grievances.
About 150 protesters held a protest last Saturday in May 1 Square, but others trying to join them were blocked by a large police presence. Algeria's biggest opposition forces are not taking part in the protest movement.