American reconnaissance satellites have reportedly spotted Chinese ships suspected of selling oil to North Korean vessels about 30 times since October.

South Korean officials told the Chosun Ilbo that the ships were allegedly trading in the West Sea between China and South Korea in a bid to bypass strict United Nations sanctions on oil exports to the pariah regime over its ongoing nuclear and weapons programme.

“We need to focus on the fact that the illicit trade started after a UN Security Council resolution in September drastically capped North Korea’s imports of refined petroleum products,” an unnamed source told the paper.

The US Treasury published surveillance photographs reportedly taken on October 19 of the North Korean vessel Rye Song Gang 1 lashed to a large Chinese vessel in deep waters, apparently showing hoses transferring oil.

Under the current tough sanctions regime Pyongyang is only allowed 500,000 barrels of oil imports a year. North Korea last week denounced ever tightening economic sanctions as “an act of war.”

Ship-to-ship trade with North Korea on the high seas is also forbidden under UN rules but very hard to patrol without an aggressive Chinese crackdown on smuggling.