The US Treasury Department in a statement on Friday announced that the move aims to choke off financing to the country's largest and most profitable petrochemical group and extends to its 39 subsidiaries and "foreign-based sales agents”, France 24 reported.
Those include UK-based NPC International and Philippines-based and NPC Alliance Corporation that are controlled by PGPIC.
"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 IRGC," US Treasury Secretary Steven Mnuchin said in the statement.
Treasury warned that international companies continuing to partner with PGPIC or subsidiaries and sales agents "will themselves be exposed to US sanctions."
Treasury said it is penalizing PGPIC due to its links to the economic arm of the IRGC, known as Khatam al-Anbiya. The holding company has awarded contracts to Khatam al-Anbiya "generating hundreds of millions of dollars for an IRGC economic conglomerate that stretches across Iran’s major industries."
Washington in April branded the IRGC a “terrorist” organization, the first time it has taken the step against part of a foreign government.
The new sanctions prohibit the firm and its subsidiaries from accessing the US market or financial system, including through other foreign companies, and blocks all funds or property that is in the United States or held by a US firm.
The penalties could extend to "any foreign financial institution that knowingly facilitates a significant financial transaction or provides significant financial services for entities designated," the statement said.
"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 PGPIC group holds 40 percent of Iran's total petrochemical production capacity and is responsible for 50 percent of the country's petrochemical exports, Treasury said.
Tensions between the US and Iran escalated, particularly after the US administration sent a carrier strike group and a bomber task force to the Middle East.
The US has ratcheted up pressure on Iran since last year after withdrawing from the 2015 nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA).
Since then, the administration of US President Donald Trump is trying to reduce Iran’s oil exports to “zero,” and has sent an aircraft carrier strike group, a bomber squad, an amphibious assault ship, and a Patriot missile battery to the Middle East to try to stack up pressure on Tehran.
Iranian officials, however, have dismissed such moves as psychological warfare, saying the country has its own ways of circumventing the American bans and selling crude oil.