Japan claims to have evidence that a Chinese company exported vehicles capable of transporting and launching missiles to North Korea last August. This would be in violation of UN trade restrictions on weapons technology, Japanese media stated.
China has denied the reports, and claims that no UN restrictions have been violated.
According to the Associated Press, Japanese authorities found that the vehicles, called TELs (for transporter, erector, launcher) were shipped from Shanghai to North Korea aboard a Cambodian flagged cargo vessel, the Harmony Wish.
TELs became the focus of international attention when in April they were displayed in a military parade in Pyongyang, North Korea's capital.
Japan's top government spokesman refused to confirm the reports, but did say that Japan will work with the international community to determine if UN regulations were violated.
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China claims the vehicles were to be used to carry lumber.
China's Foreign Ministry issued a statement in April denying any wrongdoing.
"China firmly opposes the proliferation of weapons of mass destruction and their means of delivery," said China's Foreign Ministry in a statement.
According to the Foreign Ministry, China strictly follows the relevant export control resolutions of the UN Security Council.