The State Department strongly suggested today that the Cuban government, including President Fidel Castro, has been officially involved in smuggling drugs to the United States to raise money and corrupt U.S. society.

The charges came at a Senate hearing called here to draw attention to Cuban drug connections outlined by witnesses for a federal grand jury that indicted four high Cuban officials last November.

The hearings featured an unusually explicit public accusation by the Reagan administration of official Cuban ties to drug trafficking and were believed to be the first time administration officials have publicly linked Castro to the charges.

"We have a report that the Communist Party Presidium, and specifically Fidel Castro, in early 1979 considered a scheme to begin dealing with narcotics smugglers, using Cuba as a bridge and support base for the networks to the United States as a means to aid Cuba economically and to contribute to the deterioration of American society," said James H. Michel, deputy assistant secretary of state for inter-American affairs, in prepared testimony concurred in by eight other administration officials.

Michel said evidence from the November case and other sources indicates that the plan was carried out. Alleged contact between drug smugglers and ranking Cuban officials "clearly indicates more than a case of corruption by local or mid-level security officials in Cuba" and provides a "strong indication of official policy approval," he said.

In response to questions at the hearing, Michel made the charges of official involvement even more explicit, saying "the evidence is clear that the government of Cuba has, as a matter of policy, used narcotics trafficking" to advance its goals in Latin America and the United States. Cuba has rejected similar accusations, which a recent editorial in the official Havana newspaper Granma called "wretched and cowardly tactics." The four Cuban officials indicted were never tried, since they remained in Cuba.

Today's State Department testimony was welcomed by members of the Senate Drug Enforcement Caucus, which sponsored the hearing under the chairmanship of Sen. Paula Hawkins (R-Fla.) along with Sens. Jesse Helms (R-N.C.), Jeremiah Denton (R-Ala.) and Dennis DeConcini (D-Ariz).

Helms and Denton expressed impatience with previous administration reluctance to say outright that Castro and his government are officially involved in drug running and with lack of public outrage over somewhat less explicit charges made in March, 1982, by Thomas O. Enders, assistant secretary of state for inter-American affairs.

Denton also expressed regret at the caution expressed in a television interview last weekend by FBI Director William H. Webster, who noted that most evidence of official Cuban involvement comes from one set of sources and should be viewed with care.

Denton linked the drug charges to what he portrayed as a determined effort by Cuban and Cuban-allied leftists to subvert Latin American governments, especially El Salvador's. His comments and Michel's testimony fit in with a Reagan administration campaign to rally public and congressional support for its Central American policies, including more aid for El Salvador's army.

Since last year, Michel said, U.S. intelligence has obtained evidence beyond that brought before the grand jury "confirming that Cuban officials have facilitated narcotics trafficking through the Caribbean for at least the past two years." He did not say what the evidence is or how it led to a charge that the Cuban government, rather than corrupt Cuban officials, has cooperated in drug smuggling from Colombia to Florida.

But he said the intelligence confirms in new detail a link between drug smugglers and suppliers of arms to the Colombian M19 leftist guerrilla movement, with Cuba allowing use of its waters as a haven for drug smugglers and with the smugglers taking arms from the United States to Colombia for M19.

Most of the charges center on Jaime Guillot Lara, an alleged drug smuggler wanted by the United States and Colombia.

Five persons indicted by the grand jury here last November were convicted last Feb. 25 of participating in a drug-smuggling conspiracy organized by Guillot with the cooperation of Cuban authorities.

Three self-confessed participants in the conspiracy, the main government witnesses in the trial, testified today, wearing hoods to hide their identity despite previous appearances in open court. All three expressed belief that the Cuban government cooperated officially in the conspiracy, citing contacts with high Cuban officials and a Cuban navy escort for their drug boats.

But Stanley Marcus, the U.S. district attorney here who prosecuted the case, resisted the senators' efforts to elicit a conclusion that, based on evidence he marshaled for the trial, the Cuban government is participating in drug smuggling as a matter of policy.

"I think it is a fair and accurate statement to say some of the major organs and institutions of the Cuban state and some high-ranking officials of those organs and institutions of the state are involved in drug-running to the United States," he said.

Francis M. Mullen Jr., acting administrator of the Drug Enforcement Administration, also used careful language in his testimony, saying that when all the evidence is examined, "it is difficult not to believe that the government of Cuba remains cognizant of the movement of drugs through its territory, and may be facilitating this movement."

Pressed to say whether in his opinion the Cuban government is indeed part of the drug running, he responded, "Yes."