By NANCY SAN MARTIN

A Cuba expert at Harvard University suggested Thursday that there is an unspoken alliance between the Bush administration and President Fidel Castro, drawing criticism from Cuban Americans in Miami and Washington.

Citing migration accords, joint antinarcotics operations and agricultural trade as examples of Cuba-U.S. cooperation, Jorge Domínguez, a Harvard professor of government, said the relationship between the two countries has grown under Bush despite the ''high, hostile rhetoric'' often issued by both governments

''The trend has been toward greater cooperation under the Bush administration,'' Domínguez told a gathering of more than 200 at Florida International University. He added that the alliance resulted not because the two nations were fond of each other but because it suited their respective needs.

U.S. policy toward the communist-ruled island has not changed, Domínguez said, because "Cuba is for the most part, not at all a salient issue outside of this city. It doesn't register politically outside of this city.''

The comments lit up phone lines on Spanish-language radio in Miami and drew a sharp response from Miami Republican Rep. Lincoln Díaz-Balart.

'Dominguez's theory' coincides totally with Castro's campaign to discourage Cuban Americans from voting in this year's presidential election,'' Díaz-Balart said in a statement.

''Dominguez's remarks are a clearly calculated political maneuver to weaken the Cuban-American support for President Bush,'' Díaz-Balart said.