Seoul (CNN) South Korea has seized a Hong Kong-registered ship that allegedly transferred oil to a North Korean vessel in violation of United Nations sanctions.

The South Korean Foreign Ministry said the Lighthouse Winmore left the port of Yeosu in South Korea carrying refined oil which was then transferred to a North Korean ship in international waters on October 19.

The US Treasury Department released satellite imagery in November of two ships allegedly performing an illegal ship-to-ship transfer in international waters on the same day.

Satellite imagery the US says shows a ship-to-ship transfer, possibly of oil, between two vessels in an effort to evade sanctions on North Korea.

It identified one of the ships as a sanctioned North Korean vessel, the Rye Song Gang 1, but did not name the other. The UN Security Council on Thursday added the Rye Song Gan 1 and three other vessels to a list of ships banned from docking at ports worldwide for breaching North Korea sanctions.

South Korean officials could not confirm Friday whether the second ship was the Lighthouse Winmore.

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