The United Nations has said that North Korea sent items used to make chemical weapons to Syria, in violation of sanctions.

The more than 200-page report also said the hermit kingdom on the Korean peninsula sent ballistic missile materials and technicians to the war-torn country.

The revelation of more than 40 previously unreported shipments to Syria between 2012 and 2017 comes just as the US accused the regime of Syrian President Bashar al-Assad of using what appeared to be chlorine gas in an attack on the Damascus suburb of Ghouta.

UN weapons and customs controls experts have been monitoring and writing the North Korea sanctions reports since 2010. None have been made public but this report, according to a diplomat who spoke to CNN, is set to be released 16 March.

A trade between the two countries would mean that Mr Assad continues the suspected chemical weapons attacks that harm civilians and provides money to North Korean leader Kim Jong-un to continue developing his country’s nuclear weapons programme.

Mr Assad’s government has repeatedly denied it uses chemical weapons as Syria enters its seventh year of bloody conflict.

The materials sent included “acid-resistant tiles, valves and thermometers,” the New York Times first reported.

Scenes of devastation in Syria after deadly shelling and airstrikes and eastern Ghouta

Experts monitoring Pyongyang’s compliance to UN sanctions also reported they saw North Korean missile technicians in certain Syrian facilities in 2016 and 2017.

During at least one of the visits, the technicians stayed in a Syrian military facility and North Korean scientists could still be operating in the cities of Barzeh, Adra, and Hama.

A UN spokesperson Stéphane Dujarric said during a news conference: “I think the overarching message is that all member states have a duty and responsibility to abide by the sanctions that are in place,” but did not comment on the report further.

The link between the two countries comes at a crucial time in US-North Korea relations.

Joseph Yun, the special representative for North Korea policy at the US State Department, is set to retire this week.

The Winter Olympics in Pyeongchang, South Korea, just ended and the two Koreas participated as one team in the opening and closing ceremonies.

Turkish attack on Afrin, northern Syria – in pictures Show all 9 1 /9 Turkish attack on Afrin, northern Syria – in pictures Turkish attack on Afrin, northern Syria – in pictures Smoke billows following a Turkish airstrike on a village in the Afrin district, on 28 January, 2018. Turkey launched operation "Olive Branch" on January 20 against the Kurdish People's Protection Units (YPG) militia in Afrin, supporting Syrian opposition fighters with ground troops and air strikes AFP Turkish attack on Afrin, northern Syria – in pictures Smoke billows from surrounding villages during the Turkish military operation against the Kurdish enclave on 28 January, 2018 AFP/Getty Turkish attack on Afrin, northern Syria – in pictures Twenty-year old Kifah al-Moussa, a Syrian Arab woman living among the Kurds of Afrin province, was working on a chicken farm in the village of Maryameen when a Turkish aircraft bombed the building at midday on 21 January, wounding her in the chest. When she recovered consciousness, she found eight people from one family lying dead around her Yara Ismail Turkish attack on Afrin, northern Syria – in pictures Mohamed Hussein, a 58-year-old Kurdish farmer, lies in the Afrin hospital, wounded in the head and eye after his home was bombed by Turkish aircraft on the second night of the attack Yara Ismail Turkish attack on Afrin, northern Syria – in pictures Syrian Kurds sit on benches overlooking a street in Afrin, on 28 January, 2018. Above is a memorial to ‘martyrs’ who died in the fight against Isis AFP/Getty Turkish attack on Afrin, northern Syria – in pictures Smoke is seen rising on the Syrian side of the border, at Hassa, near Hatay, southern Turkey as Turkish jet fighters hit People's Protection Unit (YPG) positions, on 28 January, 2018 AFP/Getty Turkish attack on Afrin, northern Syria – in pictures A Turkish made T-155 Firtina (Storm) howitzer is dispatched to the border at Hassa near Hatay, southern Turkey, on 28 January, 2018 AFP/Getty Turkish attack on Afrin, northern Syria – in pictures A Turkish soldier waves a flag on Mount Barsaya, northeast of Afrin, on 28 January, 2018 Reuters Turkish attack on Afrin, northern Syria – in pictures Turkey-backed Free Syrian Army fighters are seen in Barsaya mountain, northeast of Afrin, on 28 January, 2018 Reuters

One the sidelines, South Korean President Moon Jae-in and Mr Kim's sister Kim Yo Jong met face-to-face for the first time.

White House adviser Ivanka Trump was among a US delegation at the closing ceremonies after which the North Korean regime said it would be open to talks with the US.

US President Donald Trump has also yet to nominate an ambassador to South Korea. Victor Cha, who was former President George W Bush's North Korea adviser, was in the running but the administration dropped him as a candidate.

The President has had an increasingly tense relationship with Mr Kim and Mr Yun was known for advocating a diplomatic solution to denuclearising the Korean peninsula.

Mr Trump had repeatedly called Mr Kim “Rocket Man” as Mr Kim continued to test missiles dangerously close to US ally Japan last year.

For its part, the UN Security Council unanimously passed in December 2017 - including votes from Russia and China who have closer ties to Pyongyang - more sanctions on North Korea, further limiting its oil supplies and slave labour market.