The papers, on Wednesday, cited diplomats who have seen a classified UN report.
South Korean authorities inspected North Korean cargo bound for Syria and confiscated hundreds of cylinders that could be used to build the weapons, the Asahi Shimbun said.
Seoul in June reported the discovery to the United Nation's North Korea sanctions committee, which then dispatched experts to South Korea to inspect the materials, the liberal daily said.
If confirmed, the reported action shows Pyongyang violated UN bans on trading military- and weapons-related materials, imposed successively since 2006 after nuclear tests by the secretive regime.
The 445 graphite cylinders were on a Chinese-registered freighter with a cargo bound for a Syrian company with North Korean links, Kyodo News said, citing UN diplomats.
The Asahi said South Korea confiscated 535 cylinders, disguised as lead pipes that would have no connection to ballistic missiles.
The finding was included in a report filed this month to members of a special committee that is charged with overseeing the implementation of sanctions imposed on North Korea, Kyodo said.
The apparent attempt at arms exports came shortly after the UN Security Council adopted a presidential statement calling for tougher sanctions against Pyongyang, which in April attempted but failed to launch a satellite.
The launch was widely seen by other nations as cover for a missile test. The graphite cylinders found aboard the cargo ship Xin Yan Tai in South Korea's Busan port could be used for rocket nozzles and re-entry vehicle nose tips, Kyodo said.
The ship, registered in Shanghai, was built in 2005 and is owned by a Shanghai shipping company, Kyodo said, citing the China Classification Society of vessels.
The Shanghai firm's involvement in the case could pose a question over China's commitment to implementing sanctions on North Korea, Kyodo added. The interim report was prepared by a panel of experts from the five permanent members of the Security Council, Britain, China, France, Russia and the United States, as well as Japan and South Korea, Kyodo said.
Every November, the panel turns over its interim report privately to the special committee to update the 15 council members on Pyongyang's sanctions violations, Kyodo said. The interim report also says that Ukrainian authorities confirmed the arrests of two North Korean agents who attempted to steal ballistic missile technology from the former Soviet state, the Asahi said.
The panel will continue to investigate the cases involving the cylinders and the arrests in Ukraine, the Asahi added. – Sapa-AFP