The U.S. Treasury Department announced on Thursday that it would place sanctions on one domestic and four foreign subsidiaries of Iran's largest steel manufacturer, Mobarakeh Steel Company.

Sales agents for the Mobarakeh Steel Company have generated tens of millions of dollars annually from foreign sales, according to the Treasury Department statement. The five subsidiaries of Mobarakeh sanctioned include Iran-based Metil Steel, Germany-based Tara Steel Trading, and three United Arab Emirates-based companies: Pacific Steel, Better Future General Trading and Tuka Metal Trading.

"The Iranian regime continues to use profits from metal manufacturers and foreign sales agents to fund destabilizing behavior around the world," Treasury Secretary Steven Mnuchin said in the statement. "The United States remains committed to isolating key sectors of the Iranian economy until the revenues from such sectors are refocused toward the welfare of the Iranian people."

The U.S. Treasury imposed sanctions under a May 2019 executive order imposing sanctions on the iron, steel, aluminum and copper sectors of Iran.

On Thursday, the Treasury also blacklisted Iran-based Sirjan Jahan Steel Complex and Iran Central Iron Ore Company, and the South Aluminum Company, which operates in the iron and steel sectors of Iran. Together, they generate billions of dollars in sales and export of Iranian metals annually, according to the Treasury.

The Treasury also blacklisted Global Industrial and Engineering Supply, which it said knowingly transferred 300 metric tons of graphite, which is key to Iran's metal industry, to an Iranian entity on the blacklist.