The opponents, led by religious leaders from across the country, asserted that Heileman was using the name Power Master to covertly advertise the higher alcohol content in violation of Federal rules. Power Master has 31 percent more alcohol than Colt 45, which has an alcohol content of 4.5 percent.

In addition to the grass-roots campaign, whose leaders included the Rev. Calvin Butts of the Abyssinian Baptist Church in Harlem, the product was criticized by Surgeon General Antonia Novello, who contended that Heileman was aiming Power Master at young black men.

The controversy reached a fever pitch yesterday, as Heileman executives met with protesters in Chicago and with officials of the Treasury Department's Bureau of Alcohol, Tobacco and Firearms. On Tuesday, the bureau ordered the company to stop using the Power Master name. Yesterday, it announced that it had officially withdrawn its earlier approval of the Power Master label and that the company could no longer market the beverage.

But because of the earlier approval, the brewer "will be able to sell existing stocks over the next four months," Stephen E. Higgins, the bureau's director, said in a statement. Earlier Defiance

The ruling came hours after Heileman executives pledged to continue to market Power Master in the face of a boycott. The Rev. Michael Pfleger, a Roman Catholic priest on the South Side of Chicago and a leader of the protest, met for two hours with Michael Evans, a Heileman vice president, and Randy Smith, the company's general counsel, who traveled to Chicago to answer criticism about the brewery's advertising.