Beijing on Thursday said it was looking into reports from Japan that a Chinese oil tanker was delivering fuel products to a North Korean vessel at sea in breach of UN resolutions.

The UN Security Council (UNSC) prohibited the practice of transferring cargos between ships at sea in September, though the U.S., South Korea, and Japan have all reported separate incidents of DPRK ships apparently receiving fuels directly from other vessels.

The most recent example came on Tuesday when Japan’s foreign ministry released images showing a suspected ship to ship transfer involving a small Chinese oil tanker.

“We attach great