Bouteflika will take important decisions to ensure 'continuity of the state's institutions' before resigning.

ALGIERS: Algeria's President Abdelaziz Bouteflika who has faced mass protests and pressure from the army demanding he end his 20-year rule, will resign before his mandate ends on April 28, state news agency APS said on Monday.

APS said Bouteflika, who is 82 and in poor health, will take important decisions to ensure "continuity of the state's institutions" before resigning.

Earlier on Monday Algerian prosecutors announced fresh graft probes and a ban on corruption suspects leaving the country, as a government shake-up failed to halt calls for Abdelaziz Bouteflika to quit.

The ailing leader, who has rarely been seen in public since a 2013 stroke, is clinging to power in the face of mammoth demonstrations sparked by attempts to prolong his 20-year rule.

The authorities did not say who was being targeted by the new investigations into corruption and illegal money transfers abroad, but they followed the arrest of the president's key backer, businessman Ali Haddad.

Haddad, who Forbes magazine describes as one of Algeria's wealthiest entrepreneurs, was detained overnight Saturday to Sunday at a border post with neighbouring Tunisia, a security source said, without giving reasons for the arrest.

On Sunday, as rumours swirled of frantic behind-the-scenes manoeuvring, the Algerian authorities also banned all private aircraft from taking off and landing until the end of the month.

The North African state has been rocked by huge protests since Bouteflika, 82, announced in February that he was seeking a fifth term in office.

The veteran leader, whose current mandate was meant to end on April 28, said last month he was pulling out of the race but postponed scheduled elections.

The move has done little to assuage public ire and hundreds of thousands of people took to the streets of Algiers on Friday demanding the president and his entourage go.

Faced with the persistent anger, a succession of veteran Bouteflika loyalists have sought to distance themselves from the president in recent days.

Armed forces chief of staff Ahmed Gaid Salah last week called for him to step down or be declared medically unfit.

Long a faithful Boutiflika supporter, Gaid Salah said on television it was "imperative" to find a way out of the crisis "which responds to the legitimate demands" of the people in line with the constitution.

Agencies