The Algerian press this morning is unanimous about one thing: the unexpectedness of President Zeroual's announcement that he intends to leave office, 18 months before the scheduled end of his presidential term.

The President broke the news in a special television address to the nation on Friday night.

According to one of Algeria's leading French language papers, Liberté, the President's reasoning remains for the moment inscrutable.

"What has been said in the inner circles of power," the paper asks rhetorically, "to bring the president to this decision?"

Le Matin takes a similar view: it says the President's decision to step down remains for the moment inexplicable.

Ill health and political dissent

Other papers at least attempt an explanation: El-Watan accepts the theory that President Zeroual's ill health is at least in part his reason for deciding to go, but suggests that he is also exhausted by the task of attempting to overcome a lack of unanimity in political circles about how to resolve Algeria's fundamental problem: the persistent confrontation with Muslim militant factions who continue to be responsible for violent incidents.

Certainly, the ill health of President Zeroual, who is aged 57, is not imaginary. He had an operation in Geneva in May on an artery in his right leg and suffers from problems with his circulation.

His operation was a success but he has since then had regular medical check-ups.

But the underlying reason he has decided to go - analysts conclude - appears to be dissent in political circles which he has been unable to resolve, and - above all - pressure from the military men who in the last resort still apparently hold the strings of power in Algeria.

'Powerful military figures'

There have been recent press criticisms of one of his immediate political circle, his security adviser, General Mohammed Betchine, which analysts say could not have been made without the concurrence of powerful military figures.

In addition, an article in the London-based Arab newspaper El-Hayat suggests that there has been pressure from elements within the military establishment for the resignation of the Prime Minister, Mr Ahmed Ouyahya, in whom President Zeroual recently reaffirmed his confidence.

But in spite of the apparent calm with which President Zeroual's decision has been greeted in the street so far, observers in Algeria say the country will now be increasingly preoccupied with the coming presidential election.