The US has issued sanctions against a string of individuals that officials said are responsible for facilitating Iran’s support of the Houthi militant group in Yemen, including a businessman accused of arranging shipping deals.

The move by the Department of the Treasury’s Office of Foreign Asset Control (Ofac) comes in response to a series of attacks on commercial shipping that have endangered international trade in the Red Sea and Gulf of Aden.

Treasury undersecretary Brian Nelson, who oversees the department’s terrorism and financial intelligence arm, said the US will continue to work to disrupt Iran’s financial facilitation and procurement networks.

“The Houthis continue to receive funding and support from Iran, and the result is unsurprising: unprovoked attacks on civilian infrastructure and commercial shipping, disrupting maritime security and threatening international commercial trade,” he said.

Since October, multiple attacks have been launched against shipping from territory controlled by the Houthis in response to Israel’s war on Hamas in Gaza. The group has threatened to target Israeli-linked ships, but some of the vessels that have come under fire have had no apparent current link to the country.

Following those attacks, US officials have frequently cited Iran’s backing of the Houthis and have said they would consider putting the militant group back on its lists of terrorist organisations. They have also eschewed a military response to the Houthis while stating that drones shot down by a US warship they were approaching in the Red Sea may not have been targeting the vessel.

Sanctions imposed on Iran already give Ofac a tool to take action against Tehran’s support.

Ofac said the 13 individuals and entities that it added to its sanctions blacklist have provided tens of millions of dollars of foreign currency to the Houthis, an Islamic militant group that controls a swathe of north-western Yemen.

The agency said the cash was generated from the sale of Iranian commodities, backed by the Islamic Revolutionary Guard Corps’ Qods Force, which has long been on US sanctions lists over what Washington says its support of terrorism.

The new figures added to the Ofac blacklist include businessman Fadi Deniz, also known as Fadi Gazogli, whom the Treasury Department described as an ‘illicit shipping agent’ who help arrange the transportation of Iranian commodities.

The Treasury Department said Deniz organised shipments on behalf of Sa’id al-Jamal, a Houthi financial facilitator based in Iran who has already been blacklisted by US authorities, with help that included arranging payments for vessels.

Deniz, who holds identity documents from many countries, controls Deniz Capital Maritime, which the Treasury Department said was set up in part to handle business for al-Jamal’s network.

His companies, also placed on the sanctions blacklist, include Turkey and Lebanon-based Vanessa Imex Group Ithalat Ihracat Ve Dis Ticaret Limited Sirketi, Russia-based OOO Russtroi-SK, and UK-based Vanessa Group Limited and Deniz Capital LLP.

Vanessa Imex did not immediately respond to a request for comment, and contact information for Deniz and other entities he controls was not publicly available.

The new sanctions also targeted several people and companies accused of being part of al-Jamal’s network of exchange houses for moving money to Yemen.