SEOUL, South Korea — South Korea has seized a Hong Kong-flagged oil tanker accused of transferring 600 tons of refined oil to a North Korean ship in October in violation of United Nations sanctions, South Korean officials said on Friday.

The officials revealed that they had impounded the 11,253-ton tanker, the Lighthouse Winmore, and questioned its crew. The discovery came a day after President Trump accused China of letting fuel oil flow into North Korea through illicit ship-to-ship transfers on international waters.

There was no immediate evidence of official Chinese involvement in the Lighthouse Winmore’s dealings with the North Koreans.

The registered owner of the ship is a Hong Kong company called Win More Shipping. The only director of that company is Gong Ruiqiang, who lives in Guangzhou, China, according to Hong Kong corporate filings. The ship was being leased by a Taiwanese company, South Korean Foreign Ministry officials told reporters on Friday.