A father of Algeria's independence has urged the army to end the country's leadership crisis, calling ailing and incapacitated President Abdelaziz Bouteflika a despot who had been "elected and re-elected" by the military.

In a letter published on Tuesday, Mohamed Mechati did not go so far as to say the army should oust Bouteflika, hospitalised in France since April, but said "your courage and your patriotism... requires that you act swiftly for the survival of our country."

The letter, in Le Soir d'Algerie newspaper, told the army: "this president, your president, whom the Algerian people did not freely choose, has used and abused his exorbitant powers to place at his own exclusive service the institutions of the state."

"With the president now sick, the whole state is affected. These are the consequences of exercising power in a despotic way."

Mechati is one of the few surviving nationalist leaders who launched a war against colonial power France in 1954 but has remained on the sidelines of politics since independence was gained in 1962.

He urged the military, which has always chosen the country's leader, to show "courage," saying the "Algerian people will thank you for it."

Presidential elections are less than a year away, and calls have grown in the press to apply Article 88 of the constitution, which provides for the transfer of power if the head of state falls seriously ill.

Bouteflika, 76, was flown to Paris for treatment at the Val de Grace military hospital on April 27 after suffering a mini-stroke.

Regular official assurances that his condition is improving have roundly failed to convince Algerians, with media at home and in France stoking the rumour mill.

As recently as Monday, Foreign Minister Mourad Medelci insisted that Bouteflika remained actively involved in the daily running of the country.

France said last month that Bouteflika had been transferred from the Paris hospital to a new facility "to continue his convalescence" following treatment.

Bouteflika came to power in 1999. He was re-elected in 2004 and again in 2009, after changes to the constitution allowed him to run for more than two terms.

Even before the latest incident, his health was an endless source of speculation after he had surgery in Paris for a bleeding stomach ulcer in 2005 and spent a long period convalescing.