North Korea is violating international sanctions aimed at curbing its nuclear programme by exceeding a cap on petroleum imports and sending its workers overseas, including a former Juventus footballer, the United Nations said.

Pyongyang is subject to a range of restrictions imposed since 2017 that limit its oil imports and ban exports of coal, fish and textiles.

It has nonetheless continued to develop its nuclear and ballistic missile arsenal, analysts say, despite three high-profile meetings between leader Kim Jong Un and US President Donald Trump.

The UN Security Council on Monday said an annual 500,000 barrel cap on imports of refined petroleum products had been broken in just the first five months of 2020.

A report by the intergovernmental panel said deliveries to the authoritarian state "far exceeded" the ceiling, based on "imagery, data and calculations".

"The Democratic People's Republic of Korea and foreign-flagged vessels and their owners continued elaborate evasion practices" to illicitly import oil, UN experts said, using the North's official name.

The report did not say which countries had been exporting to North Korea but shipments also included luxury cars and alcohol.

China and Russia, Pyongyang's key allies, dismissed the findings, saying they were "based on assumptions and estimations".

The sun sets over the coast of North Korea, seen from Yeonpyeong Island in South Korea
The sun sets over the coast of North Korea, seen from Yeonpyeong Island in South Korea AFP / Ed JONES

The UN report said the North "continued to flout Security Council resolutions through illicit maritime exports of coal, although it suspended such exports temporarily between late January and early March 2020".

Negotiations between Pyongyang and Washington over the North's nuclear programme are at a standstill over disputes on sanctions relief and what the North would be willing to give up in return.

The report pointed out that professional footballer Han Kwang Song was transferred from Serie A club Juventus to Al-Duhail in Qatar in January in violation of UN resolutions banning North Korean nationals working overseas.

"Although the panel contacted Italy and Qatar on Mr Han's transfer immediately after the announcement, the transfer has not been cancelled," the UN report said.

The 22-year-forward was paid approximately $607,000 per year by Juventus between 2018 and January 2020, it added.

He will receive more than $5 million over the next five years from his new team under a multi-year contract.

"The panel reiterated to Qatar the relevant resolutions concerning the case," the report said.

The UN sanctions require member states to repatriate North Koreans working overseas, with a deadline to do so passing in December 2019.

But the panel said "only around 40" nations had submitted reports on efforts to send back citizens.

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