China "is shocked" by the sinking of a Chinese cargo ship by the Russian navy off the Vladivostok port and has urged Russia to give a responsible explanation as soon as possible, the Ministry of Foreign Affairs has said.

Deputy Foreign Minister Li Hui on Thursday summoned the Russian ambassador in Beijing and urged Russian authorities to complete their investigation into the incident and try their best to search for the seven Chinese crew members still missing.

"The Chinese side cannot accept and expresses its strong dissatisfaction to the Russian side over its bombardment of the cargo ship, the lack of a prompt rescue of the downed sailors and the fact that a long time has passed with no results from the investigation," Li said, according to the statement posted on the ministry's website on Friday.