The U.S. Treasury has said it has blacklisted a major Iranian port operator and the country's national airline, Iran Air.
The actions target two key segments of Iran's transport infrastructure that the Treasury said are being used to aid Tehran's efforts to develop weapons of mass destruction.
The actions prohibit U.S. entities from any transactions with Tidewater Middle East Company, which operates seven port facilities in Iran, and Iran Air, which serves 35 international and 25 domestic destinations with a fleet of about 40 aircraft.
The Treasury's designation of the firms as weapons proliferators also seeks to freeze any assets they may have under U.S. jurisdiction.
Secretary of State Hillary Clinton and Treasury Secretary Timothy Geithner condemned Iran's "dangerous activities" in a joint statement about recent measures that Washington has taken to isolate Tehran.
compiled from agency reports