The Treasury Department imposed broad sanctions Friday on Iran's petrochemical and refinery industry for contributing funds to the financial arm of Iran's Revolutionary Guard, which the State Department recently named a terrorist organization.

The sanctions target Iran’s largest and most profitable petrochemical holding group, called the Persian Gulf Petrochemical Industries Company, which maintains dozens of companies and subsidiaries.

“This action is a warning that we will continue to target holding groups and companies in the petrochemical sector and elsewhere that provide financial lifelines" to the Iranian Revolutionary Guards Corps, said Treasury Secretary Steven Mnuchin.

The Treasury Department's Office of Foreign Assets Control imposed the sanctions on the holding company's 39 subsidiary petrochemical companies and foreign-based marketing firms.

The Treasury charges the petrochemical refiners with providing financial support to Khatam al-Anbiya, the Revolutionary Guard's engineering conglomerate, which the U.S. government refers to as the "economic arm" of the group.

“By targeting this network we intend to deny funding to key elements of Iran’s petrochemical sector that provide support to the IRGC,” Mnuchin said.

The Persian Gulf Petrochemical Industries Company and its group of subsidiaries represent 40% of Iran’s total petrochemical production and 50% of Iran’s total petrochemical exports, according to the Treasury Department.