President Fernando Henrique Cardoso today demanded and got the resignation of Brazil's first civilian defense minister, Elcio Alvares, after rumors had circulated for weeks that the official had links to organized crime.

The move is likely to aggravate an already tense relationship between Cardoso and the military, which has accused his administration in recent weeks of trying to dilute the strength of what historically has been one of Brazil's most powerful institutions.

After a brief meeting with Cardoso today, Alvares announced that he was stepping down after only seven months in office. The president had made him the country's top defense official last June after combining the air force, navy and army ministries into one. Cardoso announced later today that Attorney General Geraldo Magela Quintao would replace Alvares at the Defense Ministry.

The ouster of Alvares came just weeks after one of his top aides, Solange Rezende, was forced to resign following a congressional investigation into nationwide drug trafficking found evidence that she once had links to organized crime. Both Rezende and Alvares are former officials of the state of Espirito Santo, where Alvares once served as governor and as a federal senator. It was during his time as governor that he allegedly headed a crime ring.

Reports of his alleged connections to organized crime surfaced last October, but he strongly denied them. Two months later, however, when the congressional investigation implicated Rezende, a longtime associate of Alvarez, the pressure for him to step down gathered steam.

Alvares's ouster is only the latest crisis to befall the Brazilian military in recent weeks. In late December, Brig. Walter Brauer, the air force commandant, was dismissed for insubordination after he insisted that Rezende be fired for her alleged criminal links. By the following week, both had lost their jobs.

Brauer also had complained that the government would stunt air force 's strength and independence if it forced the service to replace Brazilian-built aircraft with French-made planes. For decades, the military has contended that Brazil should not depend on foreign suppliers for basic equipment.

Brauer's dismissal created an uproar among current and former military officials, who excoriated Cardoso for the move. One former army captain, a current national legislator, suggested that the president be placed before a firing squad.

Brazil's military has long been one of the country's most influential institutions, and the country endured a military dictatorship from 1964 to 1984 before the reestablishment of democracy in 1989.