Dalian, China - President Donald Trump's administration has sanctioned the Hengli Petrochemical Refinery, China's second-largest "Teapot" refinery, over its purchasing of Iranian oil.

In a statement on Friday, the US Treasury's Office of Foreign Assets Control (OFAC) announced it would sanction the small, privately owned refinery, along with around 40 shipping vessels and firms linked to Iran.

"China-based independent teapot refineries continue to play a vital role in sustaining Iran's oil economy, and Hengli is one of Iran's largest customers for crude oil and other petroleum products, having purchased billions of dollars' worth of Iranian petroleum," OFAC wrote in the statement.

The US Navy has continued to blockade Iranian ports since April 13, in an attempt to choke Iran's economy of funds derived from the sale of oil and gas exports to countries such as China and Russia.

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"Teapot" refineries such as the Hengli Petrochemical Refinery operate as purportedly private companies, allowing them to import cheaper oil from sanctioned partners while shielding Beijing from political risk.

"Economic Fury is imposing a financial stranglehold on the Iranian regime, hampering its aggression in the Middle East, and helping to curtail its nuclear ambitions," Treasury Secretary Scott Bessent said in a statement on X.

"Treasury will continue to constrict the network of vessels, intermediaries, and buyers Iran relies on to move its oil to global markets."

The move angered Beijing, which accused the US of using trade and "illegal" unilateral sanctions as a weapon to exert control over its international partners.

"We call ‌on the US to stop politicizing trade and sci-tech issues and using them as a weapon and a tool and stop abusing various kinds of sanction to hit Chinese companies," said a spokesperson for China's US Embassy.