Tens of thousands of Algerians marched in the capital on Friday to demand that the rest of the ruling elite follow former president Abdelaziz Bouteflika in quitting power before any new election.

The 30th consecutive Friday protest also included demands that the authorities release Karim Tabou, a prominent opposition leader who has been held since Wednesday and charged with "contributing to weakening army morale".

The army, the strongest institution in Algeria, wants a presidential election as soon as possible to break the deadlock between the protesters and the authorities.

The absence of an elected president since Bouteflika resigned in April has left Africa's largest country, a major energy exporter, in constitutional limbo.

"No vote as long as the gang rules the country," read one banner, referring to interim President Abdelkader Bensaleh and Prime Minister Noureddine Bedoui, who is expected to resign soon.

"Free Tabou, free Tabou," another banner read.

Dozens of Bouteflika allies including two former prime ministers, two former intelligence chiefs, ministers and influential business tycoons have been put behind bars on corruption charges, but the protesters are calling for wider measures to overturn the old order.

Algeria is a key gas supplier to Europe and it is a U.S. partner in its fight against militant Islamist groups in the Sahara and Sahel regions.