A unit of Britain's Balli Group pleaded guilty on Friday in a US court to charges it illegally exported Boeing 747 aircraft from the United States to Iran, the US Justice Department said.

The unit, Balli Aviation, agreed to pay a USD$2 million criminal fine and be placed on corporate probation for five years, the Justice Department said in a statement.

Balli Aviation and its parent also agreed to pay USD$15 million in civil penalties in settlements with the US Treasury and Commerce Departments, although USD$2 million could be waived if there are no further export control violations.

The company was accused of violating a US embargo on Iran without first obtaining the required export license or authorization from the US government, the papers said.

"These charges reflect the commitment of the United States to vigorously enforce our laws against corporations that illegally seek to acquire US aircraft from the US on behalf of Iranian customers," Channing Phillips, acting US attorney for the District of Columbia, said in a statement.

At issue were six Boeing 747 passenger jets the company's subsidiaries and affiliates owned, three of which were leased to an Armenian airline that made them available to an Iranian private airline, Mahan Air, for flights in and out of Tehran.

The other three aircraft were not put into service.

"The US authorities viewed Mahan's involvement and the manner of its access to the capacity of the aircraft, as well as some of the steps taken by Balli Aviation to recover the aircraft and mitigate damages, to have breached US export rules," Balli Aviation said in a statement.

The United States has strict restrictions on exports to Iran, in part because of concerns that goods could also be used for military purposes. The two countries have been at loggerheads for years.