Another oil tanker was seized in South Korea for providing oil to North Korea, breaching United Nations sanctions.
OFAC said it had found three Chinese companies had cumulatively exported about $650m (about £483m) worth of goods to North Korea and cumulatively imported more than $100m (about £744m) worth of goods between January 2013 and the end of August 2017.
South Korea seized the second ship, Koti, at Pyeongtaek-Dangjin, a port on its west coast.
Four ships - three North Korean vessels and a Palau-flagged oil tanker - were blocked from global ports by the UN Security Council on Thursday over suspicions of carrying or transporting goods banned by sanctions targeting Pyongyang's weapons ambitions, according to the final list adopted by the world body.
"There will never be a friendly solution to the North Korea problem if this continues to happen".
On Friday, Seoul announced that it had seized the Hong Kong-flagged Lighthouse Winmore in late November and believed it had transferred 600 tons of refined petroleum to a North Korean ship named the Samjong No. 2.
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The announcement is the second of its kind this week, further highlighting the of use of ship-to-ship cargo transfers banned by United Nations resolutions.
Even though the Sam Jong 2 was not among the four banned vessels, it appears on a list of six other ships suspected of transporting illicit cargo, along with the Lighthouse Winmore.
President Trump lashed out at China, which he has been pressuring to exert influence over major trading partner North Korea to curb its weapons development programs, on Twitter. "We are liaising with the Korean parties concerned to obtain further information about the incident, and will take appropriate actions as necessary", the statement said.
The US had asked the Security Council to blacklist all 10 vessels, but China objected to the proposal, diplomats said, and only agreed to blacklist four ships on Thursday.
The KOTI's ties to China also seem clear, the tanker is run by companies operating out of Hong Kong and Dalian, two well-known hubs for North Korean sanctions evasion.
The resolution adopted by the council included sharply lower limits on North Korea's refined oil imports, the return home of all North Koreans working overseas within 24 months, and a crackdown on ships smuggling banned items including coal and oil to and from the country. It is Panamanian flagged.