Algeria's president Abdelaziz Bouteflika named Abdelghani Zaalane as the new director of his campaign for a fifth term, state press agency APS said on Saturday.

The decision comes a day after tens of thousands of Algerians protested against another term in office for Bouteflika, 81, who is in Switzerland for "periodic medical checks".

Opponents say the president, who suffered a stroke in 2013 and has been seen in public only a few times since, is no longer fit for the job.

Arabic language media reported on Saturday that Bouteflika's health had deteriorated to critical condition, causing doctors at the Swiss medical facility to cancel a planned operation and move him to intensive care.

Lebanese Al-Mayadeen outlet quoted a medical source in Geneva as saying the Algerian leader is in a "critical state," though Bouteflika's current health condition has yet to be confirmed.