An Irish trading company and three of its senior staff have been charged with illegally exporting helicopters and aircraft parts to Iran in violation of a US embargo.

The charges allege that Mac Aviation purchased 17 helicopter engines from Rolls-Royce in Indiana for $4.27m and exported them to Iran through companies in Malaysia and the United Arab Emirates.

Thomas McGuinn, 72, owner of Mac Aviation; his son Sean McGuinn, 40, the company's sales director; and Sean Byrne, its commercial manager, were charged with 19 counts of violating the embargo, the US Justice Department said.

Each count carries a maximum prison sentence of 10 to 20 years.

They were also charged with conspiracy, and making false statements.

The charges, which were made in July 2008, were unsealed in US federal court yesterday, a week after an Iranian man was charged in San Francisco with arranging the helicopter engine sale in violation of the embargo.

55-year-old Hossein Ali Khoshnevisrad was charged with illegally exporting and conspiracy to export US goods to Iran, charges that carry up to 65 years in prison.

The helicopter engines allegedly went to the Iranian Aircraft Manufacturing Company, known by its Persian acronym as HESA, which is on a US Treasury Department list of companies that produce weapons of mass destruction.

Mac Aviation is also accused of diverting aircraft parts to Iran Aircraft Industries and to a trading company in Dubai that appears to have sent them to Kish Island, Iran.

Mac Aviation is based in Drumcliffe, Co Sligo.

It is believed that as yet no request has been received by the Department of Justice in Dublin from the Department of Justice in Washington for the extradition of the three Sligo businessmen.

Sean McGuinn declined to comment on the allegations being made by the US Department of Justice.

Mr McGuinn said the company would be making no comment on the matter but a statement may be issued at a later stage by a solicitor.