NEW YORK • North Korea maintained and developed its nuclear and ballistic missile programmes throughout 2020 in violation of international sanctions, helping fund them with some US$300 million (S$398 million) stolen through cyber hacks, a confidential United Nations report says.

The report by independent sanctions monitors said Pyongyang "produced fissile material, maintained nuclear facilities and upgraded its ballistic missile infrastructure" while continuing to seek material and technology for those programmes from abroad.

The annual report to the Security Council's North Korea sanctions committee comes just weeks after US President Joe Biden took office.

A State Department spokesman on Monday said the administration planned a new approach to North Korea, including a full review with allies "on ongoing pressure options and the potential for any future diplomacy".

North Korean leader Kim Jong Un and then US President Donald Trump met three times in 2018 and 2019, but failed to make progress on Washington's calls for Pyongyang to give up its nuclear weapons and North Korea's demands for an end to sanctions.

In the past year, North Korea displayed new short-range, medium-range, submarine-launched and intercontinental ballistic missile systems at military parades, the UN report said. It said an unnamed member state had assessed that, judging by the size of North Korea's missiles, "it is highly likely that a nuclear device" could be mounted on to long-range, medium-range and short-range ballistic missiles.

While there were no nuclear or ballistic missile tests last year, Pyongyang "announced preparation for testing and production of new ballistic missile warheads and development of tactical nuclear weapons".

According to an unidentified country, North Korea and Iran have resumed cooperation on long-range missile development projects, including the transfer of critical parts, the monitors said. The most recent shipment was last year, they said.

In a letter in December to the UN sanctions monitors, annexed to the report, Iran's UN Ambassador Majid Takht Ravanchi said a preliminary review of the information given to it by the monitors indicated that "false information and fabricated data" may have been used in their investigation.

North Korea has been subjected to UN sanctions since 2006.

The UN monitors assessed that North Korea-linked hackers "continued to conduct operations against financial institutions and virtual currency exchange houses to generate revenue" to support its nuclear and missile programmes.

"According to one member state, (North Korea's) total theft of virtual assets, from 2019 to November 2020, is valued at approximately US$316.4 million," the report said.

In 2019, the sanctions monitors reported that North Korea made at least US$370 million by exporting coal, an activity banned under UN sanctions. But last year, they said coal shipments appeared to have been largely halted since July that year.

The isolated Asian nation imposed a strict lockdown last year amid the coronavirus pandemic that has slashed its trade, hurting an economy already burdened by international sanctions.

REUTERS