North Korea has been sending equipment to Syria that could be used to make chemical weapons, a UN report says.
Some 40 previously unreported shipments were made between 2012 and 2017, the report found. Materials included acid-resistant tiles, valves and pipes.
The report – yet to be released – said N Korean missile specialists had been seen at Syrian weapon-making centres.
The allegations follow new reports of chlorine being used by Syrian forces, which the government denies.
A second daily pause in fighting in the Eastern Ghouta region outside Damascus is due to begin, to allow in relief aid.
Aid was unable to enter the rebel-held region on Tuesday – the first of the five-hour “pauses” in fighting – after clashes continued.
Activists blamed government air and artillery strikes, while Russia said rebels had shelled a “humanitarian corridor” meant to let civilians leave.
North Korea is under international sanctions over its nuclear programme.
The report was compiled by the UN Panel of Experts, which assesses North Korea’s compliance with UN resolutions.
UN spokesman Stéphane Dujarric did not say whether the leaked report would be published, but told the New York Times: “I think the overarching message is that all member states have a duty and responsibility to abide by the sanctions that are in place.”
In a September 2017 report, which is publicly available, the group said it was “investigating reported prohibited chemical, ballistic missile and conventional arms cooperation” between Syria and North Korea.
It said that two UN member states had intercepted shipments bound for Syria, and that the goods were suspected to be supplied by North Korea’s main arms exporter as part of a contract with front companies representing the SSRC.
The Syrian government is reported to have told the UN panel that the only North Koreans present in Syria are sports coaches and athletes.
Syria signed up to the Chemical Weapons Convention and agreed to have its declared chemical weapons stock destroyed in 2013 after a Sarin nerve agent attack killed hundreds of people in rebel-held suburbs of Damascus.
The Organisation for the Prohibition of Chemical Weapons (OPCW) concluded that Sarin was used in Khan Sheikhoun, a rebel-held town in Idlib province, last April in an incident that killed more than 80 people. OPCW and UN investigators are confident the Syrian air force was to blame.
The US carried out missile strikes on a Syrian air base in response but President Bashar al-Assad maintained the incident was faked.
Suspected chlorine attacks have been recently reported in Syria, including on Sunday in the Eastern Ghouta.
The OPCW is investigating those attacks, Reuters news agency reports, citing diplomatic sources. UK Foreign Secretary Boris Johnson is among Western leaders who have suggested the Syrian government could be attacked if there is fresh “incontrovertible” evidence that chemical weapons have been used against civilians.