Iran and North Korea appear to have been regularly exchanging ballistic missile technology in violation of UN sanctions, according to a confidential report.
The report, obtained by the Reuters news agency, said the illicit technology transfers had "trans-shipment through a neighbouring third country". That country was China, several diplomats have confirmed.
The report will deepen suspicions about North Korean co-operation with Iran and heighten concerns about China's commitment to enforcing the sanctions against Tehran and Pyongyang due to their nuclear programmes.
The report was submitted on Friday to the Security Council by a UN panel of experts, a group that monitors compliance with international sanctions imposed on Pyongyang after it conducted two nuclear tests in 2006 and 2009.
The sanctions included a ban on trade in nuclear and missile technology with North Korea, as well as an arms embargo. They also banned trade with a number of North Korean firms and called for asset freezes and travel bans on some North Korean individuals.
"Prohibited ballistic missile-related items are suspected to have been transferred between the Democratic People's Republic of Korea and the Islamic Republic of Iran on regular scheduled flights of Air Koryo and Iran Air," the report said.
"For the shipment of cargo, like arms and related materiel, whose illicit nature would become apparent on any cursory physical inspection, (North) Korea seems to prefer chartered cargo flights," it said.
It added that the aircraft tended to fly "from or to air cargo hubs which lack the kind of monitoring and security to which passenger terminals and flights are now subject".
Several Security Council diplomats said China was unhappy about the report and was not likely not agree to release it to the public. At the moment, only the 15 council members have official access to the document.
One of the experts on the panel is from China and diplomats said he has never endorsed the report, which was delivered to the Security Council on Friday.
Beijing has prevented the publication of expert panel reports on North Korea and Sudan in the past. ReutersReuse content