US-Iran tensions have heightened significantly after the assassination of Gen. Qassem Soleimani's Image Credit: Gulf News

The U.S. Treasury Department Thursday sanctioned eight companies for their role in selling and buying Iranian petrochemical products through Triliance Petrochemical Company Ltd., which was sanctioned in January.

Petrochemical sales are a key source of revenue for Iran, and the U.S. alleges that the government uses it to finance a "destabilizing agenda" in the Middle East and Venezuela, Treasury said in a statement released Thursday. The agency says that Triliance uses front companies to continue selling and purchasing products from Iran.

"The United States remains committed to targeting any revenue source the Iranian regime uses to fund terrorist groups and oppress the Iranian people," Treasury Secretary Steven Mnuchin said in the statement.

At the same time the U.S. Justice Department also announced the filing of two civil forfeiture complaints involving the seizure of Iranian oil and weapons.

"The two forfeiture complaints allege sophisticated schemes by the IRGC (Iranian Revolutionary Guard Corps )to secretly ship weapons to Yemen and fuel to Venezuela, countries that pose grave threats to the security and stability of their regions," said John Demers, the assistant attorney general for the National Security Division.