The United States has imposed sanctions on five people, including a Turkish businessman, and 26 companies for allegedly facilitating oil sales on behalf of Iran.
The US Treasury Department's Office of Foreign Assets Control (OFAC) announced the measures on Thursday.
It named some of the targets as "Turkish businessman Sitki Ayan and his network of companies" as well as "Ayan's son Bahaddin Ayan, his associate Kasim Oztas, and two other Turkish citizens...," Reuters reported, citing the OFAC.
"Ayan has established business contracts to sell Iranian oil worth hundreds of millions of dollars to buyers," in China, the United Arab Emirates, and Europe, the office claimed in a statement.
The sanctions freeze the US-based assets of the targeted individuals and companies, and ban Americans from dealing with them.
The United States began a campaign of "maximum pressure" against Iran under former US president Donald Trump.
As part of the campaign, Trump took the US out of a nuclear deal between Iran and world countries, and returned all the sanctions that the accord had lifted.
On his campaign trail, his successor Joe Biden alleged an interest to return Washington to the deal. The Biden administration has, however, not only stopped short of doing so, but has also been bringing the Islamic Republic under multiple rounds of fresh economic measures, in what Tehran slams as the Biden team's continuation of Trump's anti-Iran policies.
On October 3, 2018, the International Court of Justice issued an order that temporarily, but unanimously required the US to remove any impediments on the importation of foodstuffs as well as medicines and medical devices to Iran.
The US has, however, been refraining from implementing the verdict too.