North Korea is believed to have been involved in exporting some 3.7 million tons of coal from January to August last year in defiance of U.N. resolutions, with more than 70 percent of it likely smuggled to China through ship-to-ship transfers, according to a diplomatic source.

The value of the illicit coal trade during the period is estimated to be $370 million. About $280 million of the total was from coal shipped to China after being transferred from North Korean vessels to Chinese vessels at sea, the source said.

Amid an escalating series of sanctions resolutions against Pyongyang, the U.N. Security Council in 2017 passed a measure banning key exports including coal in a bid to reduce funding for North Korea's nuclear and ballistic missile programs.

The latest information on coal smuggling was included in an annual report on North Korea sanctions violations compiled by a panel of experts.

According to the report, North Korea has continued to develop nuclear weapons with revenues earned through smuggling. The country has also strengthened and diversified its development of ballistic missiles.

The illicit coal sales to China alleged in the report were worth roughly twice the $141 million released by Chinese customs authorities as the value of all goods imported from North Korea for the same eight-month period through August 2019. It also surpassed the $215 million China reported as its total imports in 2019 from North Korea.

Following media reports of North Korea's coal-smuggling, the Chinese representative to the United Nations said in a statement that China is fulfilling its duties as set forth in the U.N. resolutions in a sincere manner.

The ship-to-ship transfer of North Korean products has been criticized as a method of evading U.N. sanctions on the country.

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