The US has reinforced its warnings that it would target booming Iranian oil exports after they hit a four-year high driven by demand from China.

The State Department said it was “robustly engaged” with the day-to-day business of enforcing its sanctions and cited two cases where it had targeted Chinese companies linked to the Iranian oil trade.

“We don’t preview potential sanctions actions, but we continue to monitor Iran’s oil exports and to engage Iran’s trading partners about the possibility of exposure to US sanctions,” said spokesman Ned Price.

His comments came after Robert Malley, the US special envoy for Iran, on Monday denied suggestions that the US was easing enforcement of its unilateral sanctions to ease pressure on global oil prices.

He said the US was intensifying talks with China to try to stem record flows of Iranian crude, with the majority bought by China.

Data analyst Vortexa said that China bought a record 1.2m barrels per day of crude in December. Total exports of 1.4m barrels per day in the month were the highest since the US reimposed sanctions after pulling out of a nuclear deal in 2018, it said.

It identified 181 tankers carrying Iranian crude in 2022, with half of them being more than 20 years of age.

“We’re not fine with it. It is one of the targets of our sanctions,” Malley told Bloomberg. “We’ve not loosened or lessened any of our sanctions since President Biden came into office, in particular, with regards to Iranian oil exports.”

The State Department cited sanctions imposed last year on a network of Iranian petrochemical producers exporting to China.

China front companies

A China-based broker, Jingfeng Gao, was included because of his involvement in multimillion-dollar transactions, according to the US.

Further sanctions linked to the network followed in September against two China-based companies for the storage and shipping of Iranian petroleum products.

China regularly challenges the legality of unilateral US sanctions at the United Nations. The world’s largest oil importer has not signed up to US-led schemes to target Russia, while upping its imports of Moscow’s cut-price crude.