He suffered a bout of bronchitis in February, forcing German Chancellor Angela Merkel at the last minute to cancel a scheduled visit to Algiers and sparking renewed speculation about his future.
"The president has not directly addressed the Algerians since 2012. No Algerian can believe that there is not a power vacuum," Ahmed Adhimi, a professor of political science at the University of Algiers, told AFP.
In a May 2012 speech, Bouteflika hinted he would give up power at the end of his third term in 2014.
But despite a stroke the following year which forced him to spend nearly three months recovering in France, he fought the 2014 election and soundly beat his longtime rival, former prime minister Ali Benflis.
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Bouteflika attended his inauguration in a wheelchair, barely able to deliver more than a few paragraphs of his speech and mumble through the oath of office.
Since then, he has rarely appeared in public, receiving foreign heads of state or government in privacy at his official residence in Zeralda, west of the capital.
But Bouteflika has clung to power, restructuring the army and intelligence services and keeping rivals at bay.
In 2015, he dismissed the Abdelkader Ait Ouarabi, a powerful counter-terrorism chief known as "General Hassan" who was later sentenced to five years in jail for destroying documents and disobeying orders.
The following day, Bouteflika dismissed secret service boss General Mohamed Mediene, a political kingmaker during his 25 years at the head of the DRS intelligence agency.
But the cancellation of the octogenarian's meeting with Merkel last month rekindled doubts about the state of political life in Algeria.
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