Algeria's powerful army chief General Ahmed Gaid Salah died of heart attack, state television reported Monday.

Gaid Salah, 79, was seen as Algeria's de facto strongman following the April resignation of longtime president Abdelaziz Bouteflika in the face of massive protests. 

The lifelong military man played a key role in pushing through December 12 presidential elections for Bouteflika's replacement, defying a months-long protest movement that has demanded deep-rooted political reforms before any poll. 

President Abdelmadjid Tebboune announced that the head of land forces, General Said Chengriha, would take over as acting chief of staff of the armed forces. 

Tebboune further announced a seven-day mourning in memory of late Gaid Salah, with national flags to fly at half mast, a statement of the presidency was quoted as saying by the APS news agency.

As chief of Algeria's military for a record 15 years and a veteran of Algeria's war for independence, the general was seen as the guardian of the military-dominated system that has been in power since.  

He had supported Bouteflika for years until the president's February announcement that he would run for re-election sparked unprecedented demonstrations.  

In early April, Gaid Salah called on his boss to resign.  

Bouteflika quit the same day, leaving the armed forces chief effectively in charge of the North African country.  

The army then backed a series of arrests of Bouteflika allies and senior businessmen in an anti-corruption campaign. 

But it was not enough to appease ordinary Algerians, many of whom had begun calling for Gaid Salah's resignation and for the military to step away from the running of the major natural gas exporter. 

Gaid Salah defied protesters by pressing on with a presidential vote on December 12. It was won by establishment insider Tebboune who was seen as close to the armed forces chief.  

The army's prominent role was underlined last week at Tebboune's inauguration, during which he embraced Gaid Salah and presented him with an order of merit immediately after his own swearing in. 

(With inputs from AFP, Reuters)