In a filing with securities regulators, the US-listed commodity trader shed light on a charter that may have involved a vessel controlled by the Islamic Republic of Iran Shipping Lines (IRISL).

When an ADM affiliate hired the ship to transport a grain cargo in the summer of last year, it said the unit and the operator were not listed on the US Department of the Treasury’s list of specially designated nationals (SDN).

After determining the vessel was beneficially owned by IRISL, a group that has been targeted by US sanctions for some time, the company voluntarily reported the matter to the Office of Foreign Asset Control (OFAC) in Washington, DC.

“The involvement of a sanctioned party was inadvertent and unintentional and we believe the result of a concerted effort by Iran to hide its ownership of the vessel,” it said.

“Neither the company nor its affiliate nor other of its subsidiaries have any intention of continuing such activity with a prohibited party.”

ADM did not identify the vessel by name in the securities filing and it’s unclear whether OFAC has pursued an investigation.

As we reported, Section 219 of the Iran Threat Reduction Act requires issuers to disclose dealings with Iran when they file annual or quarterly reports with the US Securities and Exchange Commission.

While the shipment of agricultural commodities, humanitarian aid and medicine are not prohibited under US sanctions law, legal eagles note that companies can still run into issues if the transaction involved an affiliate of one of OFAC’s SDNs or blocked persons.

Today’s revelations follow meetings between the Obama Administration and Tehran about the easing of Western sanctions, which have crippled the Iranian economy and are widely believed to be the leading cause of food and medicine shortages.