ALGIERS — Algeria's ailing leader Abdelaziz Bouteflika submitted his resignation with immediate effect, state media said Tuesday, ceding power in the face of massive street protests after two decades at the helm.

Car horns sounded on the streets before crowds of flag-waving people emerged from their homes and converged in the centre of the capital Algiers to celebrate.

Bouteflika "officially advised the Constitutional Council of the end of his term of office as President of the Republic", state television reported.

"I have the honour to formally notify you of my decision to terminate my term of office as President of the Republic from today, Tuesday," state news agency APS quoted his resignation letter as saying.

"This decision which I take in my soul and conscience is destined to contribute to the appeasement of the hearts and minds of my compatriots, to allow them to take Algeria towards a better future to which they legitimately aspire," it added.

Long accused of clinging to power, the veteran leader faced mounting pressure to step down after his decision to seek a fifth term despite rarely being seen in public since suffering a stroke in 2013.

The 82-year-old, who uses a wheelchair, said last month he would pull out of the bid for another term, and on Monday his office said he would resign before his mandate expires at the end of the month.

The moves failed to satisfy protesters who feared a ploy to extend his rule and the armed forces chief called for him to leave power.

The announcement of his resignation sparked jubilation in the capital.

Youths cheered and waved the Algerian national flag at Grande Post square, the epicentre of the protest against his rule in downtown Algiers, an AFP cameraman reported from the scene.

The United States said the future of Algeria was now up to its people.

"Questions about how to navigate this transition in Algeria, that is for the Algerian people to decide," State Department spokesman Robert Palladino told reporters.

Algeria's constitution says that once the president officially resigns the speaker of the upper house of parliament, 77-year-old Abdelkader Bensalah, would act as interim leader for up to 90 days during which a presidential election must be organised.

The resignation came shortly after the military demanded impeachment proceedings be launched against Bouteflika immediately as it dismissed the announcement he would resign before his mandate expires.

Armed forces chief Ahmed Gaid Salah called for "the immediate application of the constitutional procedure for removing the head of state from power", in a defence ministry statement after a meeting of top brass.

The statement said the army considered an announcement from the presidency on Monday that Bouteflika would resign by the end of his term on April 28 as invalid because it did not come from the president himself.

"Any decision taken outside the constitutional framework is considered null and void," the general said. — AFP