Kazem Zamani, son of a wealthy candy maker in Iran, fled to America in 1979, seeking sanctuary for himself and his family as the shah of Iran's government crumbled and the forces of the Ayatollah Ruhollah Khomeini took over.

A small bespectacled man, Zamani, 42, worked as an export-import entrepreneur and real estate manager in Maryland, living comfortably in Gaithersburg.

Now he is behind bars and is on trial in federal court here on charges of conspiring to smuggle prohibited U.S. military equipment to the same country he fled six years ago.

Zamani's arrest last June is among a series of arrests of Iranian nationals and at least one American throughout the country on charges of conspiracy to violate the U.S. Arms Export Control Act. Customs officials say demand for covert delivery of U.S. military replacement parts has grown as the U.S. equipment inherited from the shah's forces has begun to wear out in Khomeini's protracted war with Iraq.

Prosecutors say Zamani sought, among other things, to smuggle special radar components to unnamed middlemen in England for $15 million, plus numerous spare parts for aging U.S tanks, jet fighters and helicopters in Iran.

Zamani's attorney, Domenic R. Iamele, acknowledged in opening statements to the jury of nine women and three men Tuesday that Zamani had sought to sell a "laundry list" of military equipment. But the attorney contended Zamani was not aware of the U.S. ban on military sales to Iran and was "led down a path" to possibly illegal acts by a U.S. Customs undercover agent and a Gaithersburg export businessman.

Federal prosecutors Arthur F. Fergenson and Susan M. Ringler said before Judge Frank A. Kaufman that Zamani initiated the deal and entered it with his eyes wide open. He had large financial interests in London and Tehran, said Ringler, and boasted of having contacts with high-ranking Iranian officials.

Aris Mardirossian, 34, a Gaithersburg exporter and key witness in the case, testified today and yesterday that Zamani approached him in April 1984 about obtaining five Varian 145E military radar tubes from a U.S. supplier for delivery to unknown buyers in London for shipment to Iran. He said Zamani told him the London men would pay $3 million for each of the five tubes. The radar tubes sell for $50,000 to $75,000 on the U.S. open market, Mardirossian said.

Mardirossian said Zamani also discussed ways of skirting customs inspections and export license requirements by smuggling the 150-pound radar tubes on a private yacht or airplane to England or bribing an airline captain to secrete the tubes in the pilot's cabin of a commercial airplane.

Mardirossian said he notified customs agents immediately after his first contact with Zamani and agreed to work with agent George Lacey, who posed as Mardirossian's supplier for the radar tubes in subsequent dealings with Zamani.

Throughout day-long cross-examination of Mardirossian today, defense attorney Iamele sought to show that it was Lacey and Mardirossian, not Zamani, who suggested various ways to outflank the export laws. At one point, Mardirossian acknowledged that during a crucial meeting on April 17, 1984, "I was the boss of that meeting."

Iamele argued in his opening statement "that slowly my client [was] inveigled to do something that might be illegal . . . . If Lacey or Mardirossian had told him, 'You cannot export arms to Iran,' that would have been the end of it."

The trial is expected to continue for several days.