A bronze seal for the Department of the Treasury is shown at the U.S. Treasury building in Washington, U.S., January 20, 2023. Photo: REUTERS/Kevin Lamarque/File Photo/File Photo

The United States on Thursday imposed sanctions on companies it accused of playing a critical role in the production, sale and shipment of Iranian petrochemicals and petroleum to buyers in Asia, as Washington increases pressure on Tehran.

The US Treasury Department in a statement said it imposed sanctions on six Iran-based petrochemical manufacturers or their subsidiaries and three firms in Malaysia and Singapore over the production, sale and shipment of hundreds of millions of dollars worth of Iranian petrochemicals and petroleum.

The latest US move against Iranian oil smuggling comes as efforts to revive Iran’s 2015 nuclear deal have stalled and ties between the Islamic Republic and the West are increasingly strained as Iranians keep up anti-government protests.

“Iran is increasingly turning to buyers in East Asia to sell its petrochemical and petroleum products, in violation of US sanctions,” Treasury Under Secretary for Terrorism and Financial Intelligence Brian Nelson said in the statement.

“The United States remains focused on targeting Tehran’s sources of illicit revenue, and will continue to enforce its sanctions against those who wittingly facilitate this trade,” Nelson said.

Iran’s mission to the United Nations in New York did not immediately respond to a request for comment.

Thursday’s move targeted firms the Treasury accused of being involved in facilitating the sale and shipment of petroleum and petrochemicals on behalf of Triliance Petrochemical Co. Ltd., which was hit with sanctions by Washington in 2020.

Among the Iranian companies targeted were petrochemical producer Amir Kabir Petrochemical Co. (AKPC), its subsidiary Simorgh Petrochemical Co. and four subsidiaries of previously sanctioned Marun Petrochemical Co.

Treasury said Triliance has purchased millions of dollars worth of low-density polyethylene produced by AKPC for shipment to buyers in China.

Treasury accused Singapore-based Asia Fuel PTE. Ltd., which was also targeted, of facilitating the shipment of petroleum products worth millions of dollars to customers in East Asia.

Sense Shipping and Trading SDN. BHD. in Malaysia and Singapore-based Unicious Energy PTE. Ltd. were also hit with sanctions.

The action freezes any U.S. assets of those hit with sanctions and generally bars Americans from dealing with them. Those that engage in certain transactions with the companies also risk being hit with sanctions.