Thousands of police in riot gear are in position in the centre of the Algiers, the capital of Algeria, to stop a demonstration from mimicking the uprising that forced out Egypt's President Mubarak.
Officials have banned the march, setting the stage for possible clashes between police and demonstrators who are demanding greater democratic freedoms, a change of government and more jobs.
Opposition groups and rights activists say they intend to go ahead with the march.
Mr Mubarak's downfall and the overthrow of Tunisia's leader on 14 January have electrified the Arab world.
Algeria is a major oil and gas exporter. But many analysts consider an Egyptian-style revolt is unlikely because the government can use its wealth from energy to placate most grievances.
It has already cut prices for sugar and cooking oil, bought huge quantities of grain to ensure bread supplies and promised to lift a state of emergency that has been in force for 19 years.
It also says it is working hard to create jobs, build new homes and improve public services.