New York (CNN) North Korea illegally exported millions of tons of commodities like coal last year to enhance its ballistic missiles and nuclear weapons programs, according to a confidential UN report.

Prepared by a UN-appointed independent panel of experts charged with monitoring sanctions enforcement and efficacy on the Pyongyang regime, the annual report -- which has not yet been publicly released -- reveals North Korea continued its weapons program last year in violation of long-standing UN Security Council sanctions.

Investigators also concluded that "despite its extensive indigenous capability it (North Korea) uses illicit external procurement for components and technology" to develop weapons.

‎One section of the document seen by CNN said North Korea's ballistic missile program was "characterized by its intensity, diversity and coherence." The report said North Korea conducted 13 missile tests -- and launched 25 missiles -- in 2019.

North Korean leader Kim Jong Un inspects a multiple launch rocket system test in an image released by state media on November 29, 2019.

"As well as the sustained pace of launches and the variety of launch locations, 2019 saw the (Democratic People's Republic of Korea) enhance the industrial and operational dynamics of the program, with new weapon systems brought almost to operational effectiveness, increased diversity of missile types and launchers, augmentation of the Medium Range Ballistic Missile (MRBM) and Inter-Continental Ballistic Missile (ICBM) types tested through 2017," the report said.

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