Close economic ties between Pyongyang and Beijing have facilitated the transportation of freight from northeast China to its central region, Radio Free Asia reported.
A maritime route that includes the North Korean port of Rajin has enabled Chinese shippers to significantly reduce costs over a more time-consuming land route, South Korean news agency Yonhap reported.
Chinese cargo from the northeastern city of Hunchun has made the journey to bustling Shanghai twice in June, according to Chinese authorities.
Hunchun officials said 38 containers that left the city on June 24 arrived in Shanghai on June 27, and on June 11, 42 containers were delivered to China's eastern coast – all using Rajin as a key point where cargo could be loaded onto ships.
Northeast China boasts plentiful natural resources and industries such as mining and forestry. Resources in the region supply China's booming factories in the central city of Yan'an, according to South Korean news outlet Newsis.
Rajin also is part of a connectivity project between Moscow, Pyongyang and Seoul that connects North Korea to the Russian border locality of Khasan, or Hasan. Some 40,500 tons of Russian coal arrived in South Korea last November through the Hasan-Rajin railway and in April, another 47,000 tons of Russian coal arrived in South Korea from Rajin.
The announcement from Hunchun follows speculation that Kim Jong Un had been invited to attend a military parade in Beijing that would be hosted by Chinese President Xi Jinping.
The Wall Street Journal reported Kim had been invited to the Sept. 3 event, but Chinese Foreign Ministry spokeswoman Hua Chunying said Thursday she had no information on the invitation, according to Yonhap.