The Reagan administration yesterday described as "unfair and inaccurate" charges by three members of Congress that U.S. aid to El Salvador is being used overwhelmingly for military purposes, and it "categorically" rejected the assertion that it has deceived Congress about its Salvadoran policies.

The unusually tough language was contained in a statement read to reporters by State Department spokesman Bernard Kalb. Its vehemence underscored the administration's sensitivity to accusations that it seeks to overcome leftist challenges in Central America through military rather than political solutions. Kalb was responding to a report by Sen. Mark O. Hatfield (R-Ore.) and two House members that accused the administration of giving Congress false and misleading information about its activities in El Salvador.

The report's other two authors, Reps. Jim Leach (R-Iowa) and George Miller (D-Calif.), are leaders of the 130-member Arms Control and Foreign Policy Caucus, a congressional group that reflects generally liberal positions on foreign affairs. Hatfield, chairman of the Senate Appropriations Committee, is a former caucus chairman.

The report disputed President Reagan's claim that economic aid to El Salvador has been three times greater than military assistance. The critics said that only 15 percent of the $1.7 billion provided by the United States has been devoted to development and reform.

Kalb, noting that the report's authors "did not consult with the State Department or share their conclusions with us," said he could only make "some preliminary comments" before department officials had analyzed it fully.

"It is unfair and inaccurate to charge that our strategy in El Salvador is overwhelmingly military," he said. "Our program includes support for democratic institutions, a revitalization of the economy in an equitable manner, an increased security from extremist violence and support for dialogue."

Kalb took particular exception to the report's contention that $767 million, or 44 percent of total U.S. aid, has been "indirect, war-related aid" aimed at insulating the Salvadoran government and economy from war-induced collapse or assisting persons displaced by the civil war.

"Certainly, if the United States provides food, shelter and medical care for refugees, it helps the government deal with the results of the conflict, but we reject the claim that aid to refugees therefore becomes something other than humanitarian assistance," Kalb said.

He also addressed charges in the report that the administration has been misleading about U.S. military activities in El Salvador. Among other things, it alleges that the administration in various ways has dodged its promises not to increase the number of U.S. military trainers above 55.

"We never claimed that we have only 55 military personnel in El Salvador, although we have adhered to our self-imposed ceiling of 55 military trainers," Kalb said. "Congress has been regularly informed of . . . the numbers assigned to training, administration, humanitarian medical assistance, the defense attache and the embassy Marine guard detachment."

In response to the report's allegation that the administration had failed to inform all relevant congressional committees of plans to build an airport in eastern El Salvador, Kalb said: "The proposal to build a heliport in San Miguel was discussed with key congressional committees, and specifically with staff members" of the Senate Appropriations subcommittee on foreign operations.