North Korea continued to enhance its nuclear and ballistic missile programs last year in breach of United Nations sanctions, according to a confidential U.N. report seen by Reuters on Monday.

The country also illicitly imported refined petroleum and exported some $370 million worth of coal with the help of Chinese barges, the report added.

The 67-page report to the U.N. Security Council North Korea sanctions committee, which is due to be made public next month, comes as the United States tries to revive stalled denuclearization talks with North Korea.