Speaking on condition of anonymity, the diplomat told CNN News on Tuesday that North Korea had sent acid-resistant tiles, valves and thermometers to Syria. He was citing a report on North Korea authored by a UN panel of experts.
During one of the trips, the technicians stayed at Syrian military facilities. A UN member state reported to the panel of experts that scientists from North Korea may still be operating in Barzeh, Adra and Hama.
The details come just two days after the Syrian regime was accused of carrying out a chlorine gas attack on Eastern Ghouta, a suburb in Damascus.
Syrian President Bashar al-Assad's regime has repeatedly denied claims that it uses chemical weapons.
Medical aid organisations, however, said they had routinely treated victims of chemical attacks and blamed the government forces, as the country's war nears its seventh anniversary.
The US and other countries have made the same accusations against the Assad government.
"The last thing we need in Syria is more weapons ... God forbid chemical weapons," he said.
A US State Department official declined to comment on the UN report because of its confidential nature.
The official said that since 2006, "the Security Council has required the DPRK? (North Korea) to cease export of arms and related material as well as items relevant to nuclear, ballistic missiles and other weapons of mass destruction-related programmes and to fully abandon all weapons of mass destruction programmes".
The UN reports on its North Korea investigation twice a year and does not usually publicise its findings.
The diplomat, however, said this update would be released to the public on March 16.
Earlier this month, a diplomat told CNN that North Korea had earned nearly 200 million dollars from exporting coal and other banned commodities in 2017, in violation of UN sanctions.
Despite numerous rounds of international sanctions, North Korea exported almost all the commodities that had been prohibited in the resolutions between January and September of last year, the report said.
Among its coal export recipients was China, the report said. China has consistently denied breaching sanctions.(ANI)