New York (CNN) The United States and more than two dozen other countries are asking all nations to immediately halt valuable fuel shipments to North Korea.

A report submitted to the United Nations Security Council Sanctions Committee on North Korea accuses Pyongyang of violating a UN-set UN set cap on fuel imports by conducting dozens of ship-to-ship transfers at sea, which break international sanctions. The details in the report were described to CNN and others by a UN Security Council diplomat with knowledge of the findings.

The US complaint about North Korean smuggling came a day after President Donald Trump said he got another 'beautiful letter' from North Korean ruler Kim Jong Un. The White House is interested in a third summit between the two leaders.

They said the allowed annual cap of 500,000 barrels of fuel imports has been exceeded by North Korea. The report, according to the diplomat, said at least eight illegal ship to ship transfers have occurred involving North Korean flagged tankers. The diplomat said there were 72 cases of violations also being tracked.

The diplomat gave North Korea an "F" grade regarding implementation of the sanctions fuel import cap.

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