South Korea’s foreign ministry says the country has seized a Hong Kong-flagged ship that transferred oil to a North Korean vessel in international waters despite United Nations Security Council sanctions.

Yonhap, the South Korean news agency, reports South Korean custom officials say the Lighthouse Winmore vessel transferred “600 tons of refined petroleum” to a North Korean ship October 19. South Korea seized the Lighthouse Winmore on November 24 when it sailed into South Korea’s Yeosu Port, the news agency says.

Yonhap reports the Lighthouse Winmore was chartered by the Billions Bunker Group, a Taiwanese company. The news agency said the ship’s “claimed destination” was in Taiwan, but instead the ship “transferred oil to a North Korean ship, Sam Jong 2, and three other non-North Korean vessels in international waters in the East China Sea.”