The Treasury also identified eight aliases used by a sanctioned Chinese company, LIMMT Economic and Trade Company, Ltd., that it said were used to circumvent sanctions.
The Treasury Department said it was taking the actions under an executive order "aimed at freezing the assets of weapons of mass destruction proliferators and those who support them."
Five companies were sanctioned for allegedly being tied to Iran's Defense Industries Organization (DIO): Khorasan Metallurgy Industries, Kaveh Cutting Tools Company, the Amin Industrial Complex, Yazd Metallurgy Industries, and Shahid Sayyade Shirazi Industries.
Another Iranian entity, the Niru Battery Manufacturing Company, was targeted for its links to the Iranian Ministry of Defense and Armed Forces Logistics (MODAFL).
Both DIO and MODAFL had been blacklisted by the State Department for having engaged in "activities that materially contributed to the development of Iran's nuclear and missile programs," the Treasury said.
The Treasury said it had imposed a sanction against a Chinese individual, Li Fangwei, also known as Karl Lee, the commercial manager of LIMMT, a Chinese firm that had been blacklisted in 2006 "for providing material support to Iran's missile program."
To circumvent the 2006 sanction, Lee allegedly created front companies to access the global financial system.
The Treasury added the names of eight such LIMMT front companies as aliases to its list of "specially designated nationals."
The companies were named as Ansi Metallurgy Industry Co. Ltd.; Blue Sky Industry Corporation; Dalian Carbon Co., Ltd.; Dalian Sunny Industry & Trade Co., Ltd.; Liaoning Industry and Trade Co., Ltd; SC (Dalian) Industry & Trade Co., Ltd.; Sino Metallurgy & Minmetals Industry Co., Ltd; and Wealthy Ocean Enterprises Ltd.
The Treasury noted that the United Nations Security Council had designated Khorasan Metallurgy Industries for sanctions in a 2008 resolution and identified Khorasan as involved in the production of centrifuge components.
The same year the Security Council slapped sanctions on Niru Battery Manufacturing Company, saying the firm made power units for the Iranian military, to include missile systems.
"Today we are acting under our Security Council and other international obligations to prevent these entities from abusing the financial system to pursue centrifuge and missile technology for Iran," said the US under secretary for terrorism and financial intelligence, Stuart Levey.
The sanctions mean any assets held by the six Iranian firms or Lee under US jurisdiction are frozen and US citizens are barred from dealing with them.
Washington has steadily upped sanctions against Iranian businesses and financial institutions in recent months in hopes of pressuring Tehran to pull back on its nuclear program — which the US says is aimed at developing nuclear weapons — and to halt its alleged support for groups Washington has labeled "terrorist," including Lebanon's Hezbollah and armed Palestinian groups.
