Kazem Zamani, a Gaithersburg businessman accused of conspiring to ship millions of dollars in prohibited U.S. military equipment to his native Iran, pleaded guilty today in U.S. District Court.

In an agreement arranged with prosecutors, Zamani, 42, pleaded guilty to one count of violating the U.S. Arms Export Control Act and agreed to cooperate in government investigations aimed at stopping the covert shipment of U.S. weapons to Iran and other countries.

In exchange, the government recommended that Zamani be sentenced to 18 months in prison and fined $10,000.

No sentencing date has been set, but Chief Judge Frank A. Kaufman could send Zamani to prison for as long as five years and fine him as much as $125,000.

The government also has agreed not to deport Zamani, a key element in his decision to plead guilty, according to defense attorney Domenic R. Iamele.

A two-week trial on the conspiracy charge ended in a mistrial last month when the jury declared itself deadlocked after five days of deliberations. Afterward, jurors reported they were split 10 to 2 in favor of conviction, and Iamele said that was a factor in accepting today's plea agreement.

Zamani was arrested in June after a lengthy undercover investigation by U.S. Customs Service officials.

The government alleged that Zamani conspired with "others unknown" to smuggle radar components to unnamed middlemen in England for $15 million, plus spare parts for U.S. Cobra attack helicopters, tanks, jet fighters and other military equipment.

The Iranian regime of Ayatollah Ruhollah Khomeini seized millions of dollars in U.S. military equipment left behind in Iran after the fall of the shah in 1979. Government officials say Iran has been using that equipment in its six-year-long war with Iraq and needs replacement parts for much of it.

Under the terms of today's plea agreement, Zamani is required to tell government investigators whatever he knows about the trade in illegal arms and could be required to testify as a government witness in other arms-smuggling trials.

Zamani, the son of a wealthy candy manufacturer, fled Iran in 1979 when the Khomeini government came to power.

He and his family settled in Gaithersburg.

There he went into business as a real estate manager and an import-export entrepreneur. Prosecutors have said Zamani has assets worth more than $1 million in this country, Europe and Iran.

The investigation of Zamani began after he allegedly approached Aris Mardirossian, a Gaithersburg exporter, in April 1984 about obtaining five military radar tubes from a U.S. supplier for delivery to Iran via middlemen in London.

During Zamani's trial last month, Mardirossian testified that Zamani discussed ways to get around customs inspections and export license requirements. Mardirossian told Customs officials about his conversation with Zamani and agreed to work with an undercover agent.

Before today's guilty plea, Zamani had maintained that he was unaware of the ban on the export of military equipment and that he was entrapped by federal agents. Zamani remains in federal custody.