WASHINGTON - The U.S. government has ordered the expulsion of two Cuban diplomats at the United Nations, one of them the head of Cuba's intelligence service in New York, the State Department said Tuesday.

The Cuban mission's second secretary, Mario Monzon Barata, and his assistant, Jose Rodriguez, "must depart the United States expeditiously," State Department spokesman Dean Fischer said.

Fischer's official announcement accused the two Cubans of violating the Trading With the Enemy Act, "by buying, and trying to buy, large quantities of high-technology electronic equipment, much of it subject to strategic trade controls.

The expulsion, said Fischer, stems from the confiscation last Thursday in Orlando of $38,000 worth television satellite monitoring equipment.  Fischer said the U.S. Customs Service and the FBI had linked the equipment to a mail-order purchase by Monzon Barata.

Fischer identified Monzon Barata as the New York chief of Cuba's Directorate General of Intelligence (DGI), and said that FBI "counterintelligence investigations" had established that the Cuban had "been engaged in intelligence gathering."

A State Department official said Monzon Barata had violated the Trading With the Enemy Act "for over a year" by purchasing other pieces of electronic equipment.

The official said all of this equipment already had been shipped to Havana. He added that U.S. intelligence officials were "reasonably sure that some of it was later shipped to the Soviet Union.

In New York, the Cuban Mission to the U.N. declined comment and in Washington the Cuban Interest Section said its chief, Ramon Sanchez Parodi, still had not been officially notified of the expulsion order.

But diplomatic sources close to the mission said that "even if the equipment was bought, it was not sent to the Soviet Union or was not bought to spy."

"Anybody in this country is allowed to buy this type of equipment," one of the sources said.

The expulsion order was communicated Monday to the Cuban mission at the United Nations, Fischer said.  He gave no date for the departure of the diplomats.

An FBI spokesman said Tuesday that he knew of specific purpose for the satellite equipment, adding that the main charge against the Cubans was the violation of the Trading With the Enemy Act.  He added that even if the FBI knew the specific intelligence use of the gear, "we would not discuss it, because it would be classified."

It was the second expulsion of Cuban diplomats from the United States since the Reagan Administration came to power in January 1981.

On Feb. 11, 1981, the State Department expelled the second-ranking Cuban diplomat in the country - Ricardo Escartin, first secretary of the Cuban Interest Section in Washington - who was accused of engaging in intelligence activities and conspiring with U.S. businessmen to violate the embargo on U.S. trade with Cuba.

The 1981 Cuban expulsion was the first since 1970, when two members of the Cuban mission to the United Nations were ordered to leave.