A Chinese-flagged ship - thought to be carrying missile parts from North Korea - destined for Syria has been stopped by South Korean authorities, it has emerged.
The container vessel, the Xin Yan Tai, was impounded at the South Korean port of Busan in May this year, according to diplomatic officials at the United Nations in New York.
Within the ship's cargo, authorities claim to have found 445 graphite cylinders that could be used in a missile programme.
The shipment had been declared as lead piping. The cylinders are believed to have originated in North Korea.
According to South Korean diplomats, the shipment was destined for a Syrian company called Electric Parts.
"It appears the cylinders were intended for Syria's missile programme," a diplomat told Reuters news agency. "China assured us they will investigate what looks like a violation of UN sanctions."
China has said that it will investigate the discovery, which would be a violation of UN Resolutions.
Foreign Ministry spokesman Hong Lei, speaking in Beijing, said China strictly followed UN resolutions and its own non-proliferation export controls.
"China will handle behaviour that violates relevant UN Security Council resolutions and China's laws and regulations according to the law," he said.
China's willingness to investigate has been welcomed by diplomats in New York.
"It's possible that the crew of the Chinese ship had no idea what this shipment really was. It's good that China's expressed a willingness to investigate," one official said on condition of anonymity.
The link between the North Korean exporter and Syria is not clear, although diplomats suggested the Syrian firm may be a subsidiary of the North Korean one.
The US and EU has imposed sanctions on Syria but there is no UN arms embargo against Syrian President Bashar al Assad's government.
President Assad has waged a 20-month military campaign against armed opposition. Some 30,000 people are said to have died in the violence.