The report said UN sanctions monitors had "found evidence of a consistent trend on the part of the DPRK (Democratic People's Republic of Korea) to disperse its assembly, storage and testing locations”, World News reported.
The report seen by Reuters on Monday was sent to a 15-member UN Security Council sanctions committee ahead of a second summitbetween North Korean leader Kim Jong-un and US President Donald Trump later this month.
In the wake of the first summit between Trump and Kim, which was held in June in Singapore, they agreed to work toward denuclearization, but that agreement, made in a written document, was broadly worded.
Subsequent diplomacy between the two sides has also made little progress in recent months, mainly because the US refuses to lift harsh sanctions on the North.
The UN report also added that harsh sanctions on North Korea were proving ineffective.
"The country continues to defy Security Council resolutions through a massive increase in illegal ship-to-ship transfers of petroleum products and coal," the report said, adding, "These violations render the latest UN sanctions ineffective."
The council has imposed a series of strong economic sanctions against North Korea over its nuclear and ballistic missile tests.
The monitors announced that they had detected "new sanctions evasion techniques that defeated the due diligence efforts of the region's leading commodity trader, as well as the US and Singaporean banks that facilitated the fuel payments and a leading UK insurer that provided protection and indemnity cover to one of the vessels involved".
Since the last summit in Singapore, the North has suspended missile and nuclear testing, demolished at least one nuclear test site, and agreed to allow international inspectors into a missile engine test facility and another nuclear testing site.
North Korean authorities, however, have complained about continued US and UN sanctions, calling them a “source of mistrust”.
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