A Panama-flagged tanker named Koti, has been seized by South Korean authorities who suspect that the ship may have supplied oil to its neighbours, North Korea in violation of worldwide sanction.
Beijing on Friday denied selling oil products to North Korea even though the Lighthouse Winmore is owned by a company registered in Guangzhou, while the vessel sails under a Hong Kong-flag.
The crews of both the impounded vessels are mostly Chinese, raising suspicions that China - North Korea's largest trading partner - may be supplying the fuel, or failing to do enough to prevent its sale.
The ship, which can carry 5,100 metric tons of oil, is now docked in Pyeongtaek-Dangjin port on South Korea's west coast after security officials reportedly decided on December 21 not to allow the vessel to leave the port, according to Yonhap citing a local maritime office.
It did not include even harsher measures sought by Washington that would ban all oil imports and freeze global assets of the government and its leader Kim Jong Un. The Hong Kong-registered Lighthouse Winmore, which was chartered by a Taiwanese company, was seized at the South's port of Yeosu in November for allegedly transferring refined petroleum products to the North's Sam Jong 2.
The Lighthouse Winmore visited Yeosu on October 11 and loaded some 14,000 tonnes of Japanese refined oil before heading towards its purported destination in Taiwan.
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The committee has opened a criminal investigation into "an attempt to kill two or more persons in a generally risky way". The evacuation has been completed, and there was no fire", a local Emergencies Ministry official told TASS news agency.
Instead of going to Taiwan, however, the vessel transferred 600 tonnes of oil to the North's Sam Jong 2 in worldwide waters off China before returning to Yeosu, the customs service officials said.
"The vessels are smuggling Russian fuel from Russian Far Eastern ports to North Korea".
Speaking on condition of anonymity, one western security source said: "Russian vessels have made ship-to-ship transfers of petrochemicals to North Korean vessels on several occasions this year in breach of sanctions".
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 council has unanimously approved several rounds of sanctions against North Korea over its missile tests and nuclear programme, including a tough new United Nations resolution earlier this month.