The Obama administration penalised nearly three dozen companies and individuals in eight countries on Thursday, accusing them of evading sanctions on doing business with Iran.

It was the administration’s most extensive enforcement action to target Iran since a temporary international agreement on that country’s disputed nuclear program was completed in November and put into effect last month.

Announced by the Treasury Department office that oversees sanctions enforcement, the punishments were at least partly devised to send a message that the U.S. is not relaxing economic pressures on Iran, apparently to blunt an atmosphere of optimism that has resulted from the temporary nuclear agreement. This week, Secretary of State John Kerry criticised France after it sent a large trade delegation to Iran.

“Today’s action should leave no doubt that those who seek to evade our sanctions, support Iran’s nuclear program or assist in Iran’s promotion of international terrorism will continue to be called to account,” a senior Treasury Department official said in a conference call with reporters.

A Treasury announcement said the enforcement action had singled out “a diverse range of entities and individuals located around the world” for evading U.S. sanctions aimed at Iran.

There was no immediate comment from the Iranian government.

Under U.S. sanctions laws and regulations, violators face severe penalties, including restrictions on doing business in the United States and the seizure of any property under U.S. jurisdiction.

Eighteen businesses and 14 individuals were identified as violators in the Treasury announcement, in a list of countries that included Turkey, Spain, Germany, Georgia, Afghanistan, the United Arab Emirates and Liechtenstein.

Some were accused of helping Iran circumvent U.S. sanctions on financial transactions and oil sales. Others were accused of involvement in what the U.S. regards as Iran’s illicit activities in Afghanistan and Syria.

A Spanish company, Advance Electrical and Industrial Technologies SL, and its sole shareholder, Pere Punti, were penalised for helping Iran procure specialized nuclear equipment. A Turkish citizen, Ali Canko, was penalised for helping an Iranian company’s attempts to reverse-engineer an armed speedboat to be used by Iran’s Islamic Revolutionary Guards Corps. An Iranian-owned airline in the United Arab Emirates, Blue Sky Aviation, was accused of obscuring banned financial payments for aircraft, engines and parts.

An Uzbek citizen, Olimzhon Adkhamovich Sadikov, was identified by the Treasury as a facilitator of what it called an al-Qaeda network in Iran that operates with the knowledge of Iranian authorities — even though they have a well-known animosity toward al-Qaeda. New York Times News Service

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