The US Treasury said the Chinese companies shipped centrifuges for producing fuels, non-ferrous metals with potential military use, electronics and gyroscopes to already-sanctioned Iranian government bodies and private companies closely involved in building the missiles.

Washington is concerned that Iran plans to develop nuclear weapons that could be loaded on ballistic missiles to menace Israel and other countries.

The companies include Beijing Shiny Nights Technology Development, Qingdao Zhongrongtong Trade Development, Hong Kong Ke.Do International Trade Co, Lingoe Process Engineering Limited and Zhejiang Qingji Ind. Co.

The US Treasury also placed sanctions on Iran's defense attache in Beijing, Davoud Damghani, saying he coordinated purchasing of Chinese supplies for Iran's defense industry.

The sanctions ban US firms and individuals and companies like global banks with US branches from doing business with those placed on the blacklist.

"Today's action reinforces our commitment to respond to activities which undermine regional stability and threaten the security of our key partners and allies," said Treasury Under Secretary Brian Nelson.

"The United States will continue to target illicit transnational procurement networks that covertly support Iran's ballistic missile production and other military programs," he said in a statement.