The United States on Monday announced new sanctions on a Chinese businessman and several companies for selling to Iran items banned under U.S. laws aimed at curbing that country's missile program.
A notice published on the Federal Register website marks at least the third time since 2006 that Li Fangwei, also known as Karl Lee, has faced U.S. penalties for supplying material and support to Iran's missile development.
(Read More: EU Imposes Toughest Sanctions Yet Against Iran)
The notice said Li and a firm called Dalian Sunny Industries "have engaged in missile technology proliferation activities that require the imposition of missile sanctions" under the U.S. Arms Control Act and the Export Administration Act.
A separate sanction notice listed Li, Dalian Sunny, and three other Chinese firms, including Poly Technologies Incorporated, as being sanctioned for violations of the Iran, North Korea, and Syria Nonproliferation Act.
The other two Chinese firms, BST Technology and Trade Company and China Precision Machinery Import and Export Corporation (CPMIEC), were on a list that also included companies from Belarus, Iran, Sudan, Syria and Venezuela.
The decision to impose sanctions was taken on December 20 and took effect on February 5, said the notices.
The notices did not specify what banned products were sold to Iran, Syria or North Korea. But they said the sales violated rules of the Missile Technology Control Regime, the Chemical Weapons Convention, the Nuclear Suppliers Group and other international programs aimed at curbing the development and proliferation of weapons of mass destruction.
(Read More: North Korea Threatens 'Strong' Measures Than Nuclear Test)
Poly Technologies Inc, a major arms firm, did not answer telephones in Beijing on Monday, a national holiday in China.
But China's state-run Xinhua News Agency carried a statement from Poly Technologies saying the accusations against the subsidiary of the state-owned conglomerate China Poly Group Corporation were baseless.
"We have never helped any countries or regions develop any banned weapons, nor have we exported or promised to export weapons or technologies to any countries or regions that are under United Nations Security Council Resolutions Sanctions," the firm was quoted as saying.
"We hereby demand the U.S. side to respect the fact and immediately lift the sanctions," said Poly Technologies.
Chinese Foreign Ministry spokeswoman Hua Chunying, in a statement published on the ministry's website on Monday, said the new U.S. sanctions decision "seriously violates the norms of international relations and harms China's interests."
Hua's statement did not address the specific allegations behind the sanctions or mention any companies by name.
"China urges the United States to immediately correct its mistaken policy and revoke these irrational sanctions toward the relevant companies and individuals and cease taking actions that harm China's interests and China-U.S. relations," the statement said.
A U.S. State Department official told Reuters Li and Dalian Sunny were being sanctioned "for proliferation to Iran."
"Certainly the sales are from more recent times, since 2009," - when Li was placed under sanctions for similar sales of banned items - the official said.
Li has previously denied that he has exported illegal items to Iran.
In 2006, the U.S. Treasury barred Li and the LIMMT Economic and Trade Company from the U.S. financial system for selling goods with potential military uses to Iran - something U.S. officials said Li denied.
Three years later, the New York County District Attorney unsealed a fraud indictment against Li and the Dalian-based LIMMT Economic and Trade Company, for using false names to process further payments for sales to Iran through U.S. banks.
(Read More: Iran Oil Exports to Asia Fell by a Quarter in 2012)
Dalian Sunny Industries and LIMMT Economic and Trade Company are two of more than 25 names used by the LIMMT Metallurgy and Minerals Company, according to the Iran Watch website of the Wisconsin Project on Nuclear Arms Control.
Lee and the firm will for two years face the denial of all new individual export licenses and U.S. government contracts relating to items and materials controlled under the Missile Technology Control Regime, a voluntary international effort to halt proliferation of weapons of mass destruction.
The other sanctioned firms are barred from doing business with or receiving assistance from the U.S. government.