A Russian-operated boat has been involved in facilitating North Korean cargo shipments to China at a time when international sanctions against Pyongyang over its missile and nuclear programs are squeezing trade between the two countries, a source close to the matter said Saturday.

Goods carried by the boat, named Mangyongbong, from North Korea to Russia have been reloaded onto a non-North Korean vessel for shipment to China, in an apparent attempt by the reclusive state to continue international trade.

According to bills of lading dated Sept. 14 and Sept. 29 obtained by Kyodo News, the Mangyongbong transported 16 tons of aluminum from Rason in northeastern North Korea to Vladivostok, with a plan to reload the cargo onto a non-North Korean ship bound for Foshan in southeastern China. The Mangyongbong returned to Rason with tobacco and mahjong game tables, according to the source.

InvestStroiTrest, operator of the Mangyongbong, told Kyodo News it undertook the work following the closure of sea routes between China and North Korea. It said aluminum is not included in the list banned by the U.N. sanctions against North Korea.

InvestStroiTrest started the first regular ferry service using the Mangyongbong between Russia and North Korea in May this year. It halted the operations in August after it was unable to pay docking fees at Vladivostok.

Responding to a request by North Korea at the end of September, the Russian firm carried cargo on the Mangyongbong in a round trip between Rason and Vladivostok with no passengers.

InvestStroiTrest intends to continue the service between Rason and Vladivostok, the source said.