Large numbers of police vehicles lined both sides of key roads in the city centre, hindering movement of protesters calling for 'civil disobedience'.

Algerians descended on the capital in huge numbers on Friday and called for “civil disobedience" for the first time in their months-long anti-regime campaign, despite a heavy police presence.

"Civil disobedience is coming!" protesters shouted, as they marched calmly through the centre of Algiers.

Mass demonstrations began in February against the two-decade rule of ailing president Abdelaziz Bouteflika, who was forced to step down in April.

Protesters have continued to take to the streets, calling for the fall of other regime insiders, including army chief Ahmed Gaid Salah and Bouteflika's interim replacement Abdelkader Bensalah.

"Salah - resign!" the protesters shouted.

Large numbers of police vehicles lined both sides of key roads in the city centre, hindering movement, while they also blocked access via secondary roads.

Thousands of officers - some in uniform, including riot gear; others in plain clothes - were deployed and a dozen people arrested in the morning, before being taken away in police vans.

The deadlock between the authorities and the protest movement has tightened since de facto strongman Gaid Salah on Tuesday "categorically" rejected pre-conditions to launching talks.

The protest movement has been calling for key measures to be taken before any dialogue, including lifting police roadblocks around Algiers and ending other efforts to impede marches.

Protesters are also demanding the release of people arrested in connection to demonstrations as a prerequisite to talks.

A trader on Friday appeared perplexed by the authorities' refusal to cede ground.

"Why has Gaid refused measures to calm things down?" asked 67-year-old Hocine Slimani.

"Why leave young protesters in prison? How is it possible to talk in these conditions?”

Last month, Youcef Yousfi was the latest among a series of prominent politicians and businessmen to be detained or questioned in connection with corruption since longtime leader Bouteflika resigned in April in the face of mass protests against his rule.

Yousfi, who served between 2017 and 2019, is under investigation for graft and is suspected among other things of "squandering public funds" as well as "abuse of power and conflict of interest", the state broadcaster said.

He was placed under preventive detention by the supreme court's investigating magistrate, it said.

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