Washington has already blacklisted Iranian entities and banks for their apparent links and support of Iran's nuclear programs. Tehran has steadfastly denied it is pursuing nuclear arms, and says its nuclear ambitions are peaceful.

"Responsible financial institutions and businesses worldwide are taking steps to avoid doing business with Iranian nuclear and missile entities, as well as with the front companies and cut-outs the Iranian regime uses to disguise its activities," said Stuart Levey, a senior Treasury official.

The five entities were identified as the Nuclear Research Center for Agriculture and Medicine, the Esfahan National Fuel Research and Production Center, Jabber Ibn Hayan, Safety Equipment Procurement Company and Joza Industrial Company.

"These five nuclear and missile entities have been used by Iran to hide its illicit conduct and further its dangerous nuclear ambitions," Levey charged.

The sanctions bar any US citizen from business dealings with the Iranian groups and also freezes any assets the groups may have under US jurisdiction.

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