US surveillance photographs have captured an activity where Chinese ships sold oil to North Korean ships some 30 times, a South Korean news service said in a statement.
Chosunilbo quoted from South Korean government sources as revealing photos showing activity in the West Sea between China and South Korea.
"We need to focus on the fact that illicit trafficking begins after a UN Security Council resolution in September drastically limits the import of refined North Korean oil products," the news service quoted a government official as saying. / 12/2017).
Pyongyang is now allowed to import 500,000 barrels of oil annually.
North Korea says it is just a "dream" for the United States to think that North Korea will release its nuclear weapons, and called the latest UN sanctions to target the country under Kim Jong-un's regime is "an act of war" sovereignty.
The UN Security Council has unanimously approved new sanctions against North Korea on Friday in response to a new ballistic missile launch which Pyongyang says could reach the US mainland targets wherever it may reside.
The resolution was compiled by the United States and negotiated with North Korea's closest ally, China. The final update, however, can increase the tension between the two partners who do not cooperate.