Algerian President Houari Boumediene has a blood clot in his brain that caused the coma he has been in for several days, according to diplomatic sources here, who quoted doctors in Algiers.

He is being treated by teams of doctors from the United States, the Soviet Union, France, Britain, Yugoslavia and Tunisia.

The consensus of the doctors seems to favor a delicate and dangerous operation, the sources said. According to essentially pessimistic diagnoses reaching here, it seems doubtful that Boumediene could regain enough of his health rapidly enough to rule in the foreseeable future - even if the operation were successful.

"Politically, Boumediene is already dead," a top French official said this week.

THe eight-man Council of the Revolution has been meeting daily to run the country on a interim basis. Although the council of military men has no formal role in the Algerian constitution, all the analysts agree that it is the power center from which Boumediene's successor is likely to emerge.

In addition to the blood clot, the medical reports are that Boumediene is being mantained on a kidney machine.

In addition to being president, Boumediene is also defense minister and head of the National Liberation Front, Algeria's only legal party.

When he overthrew his predecessor, Ahmed Ben Bella, in 1965. Boumediene was armed forces chief of staff. After becoming president, Boumediene appointed a new chief of staff who attempted an unsuccessful coup d'etat of his own. Boumediene has since left the office vacant and in effect occupied it himself.

The Council of the Revolution, formed to support Boumediene, originally had 24 members, but it has been reduced to a small and secretive nucleus of men locked in an intricate web of personal alliances and rivalries.

In France, which fought a long war to try to prevent Algerian independence, there are many people who worked intimately with the National Liberation Front against the continuation of French rule. Many of those French citizens have maintained close ties with Algeria.

The close personal and political ties they have maintained with the Algerian leaders are the main source of what little information filters out about the workings of Algeria's inner circle.

These sources say that the leadership group is concerned enough about Algeria's prestige and international image that they will do all they can to prevent their struggle for power from erupting openly. If Boumediene's illness continues for a while, it will provide time for the council to try to settle the succession problem.

According to French sources close to the Algerian leaders, a succession struggle has already started with a lineup of two groups inside the Council.

The most powerful of the two clans includes the commanders of the two most important military regions outside of the central region around Algiers, the capital. Those two officiers, Col. Abdallah Belhouchet and Col. Chadli Benjeddid, are the only troop commanders left in the council. They are considered to be allied to two other powerful council members, Transport Minister Ahmed Draia, head of the national police until last year, and, above all, Col. Mohammed Salah Yahiaoui.

As the man behind Boumediene in the Liberation Front's hierarchy, Yahiaoui controls the daily functioning of the party apparatus. He was the commander of the Algerian military academy for eight years and was in charge of training the rising new generation of Algerian officers. By all accounts, he is popular with the young officers.

At least one of this powerful group of four is also particularly close to Foreign Minister Abdelaziz Bouteflika, a personal protege of Boumediene and a man with wide support in the government bureaucracy.