South Korea breached UN rules by failing to report more than 300 tonnes of petroleum products sent to North Korea in 2018, according to a report published Wednesday.

The discrepancy was revealed by the NK News website, which monitors and tracks North Korean activity.

Any UN member sending petroleum products to North Korea is subject to strict regulations and reporting requirements. Under UN Security Council resolution 2397, adopted in 2017, member states must notify a sanctions committee every 30 days of the amount of refined petroleum products supplied, sold or transferred to Pyongyang.

“We only used petroleum products to carry out joint inter-Korean projects, and our view is that this does not harm the purpose of sanctions on North Korea,” South Korea’s foreign ministry told Reuters Wednesday.

The UN Security Council said that only Russia and China — two of North Korea’s main trading partners — provided the necessary documentation in 2018.

The revelation comes amid a standstill on denuclearization talks between Washington and Pyongyang, which Kim Jong Un blames on the Trump administration refusing to loosen sanctions.

Secretary of State Mike Pompeo said Tuesday there “remains an awful lot of work to do” on denuclearization but added that by the end of next month “we’ll have another good marker along the way” with North Korea.

Pompeo was referring to the news that Trump will hold a second summit with Kim at the end of February, adding that “good things have happened already” since the pair’s first meeting in June.

Speaking to the World Economic Forum via video link, Pompeo said that the private sector would have an important role to play in helping North Korea develop.

“If we’re able to achieve that full denuclearization that I know the entire world wants, the private sector will be an important player in achieving the final elements of the agreement as well,” Pompeo said.

Separately, the Security Council announced this week that it had lifted sanctions for four humanitarian agencies to visit North Korea, allowing them to send supplies such as medicine, ambulances and computers.