Two Chinese naval vessels have left North Korea after a four-day visit, marking 50 years of friendship between the two countries.

The training ship Zheng He and the frigate Luoyang set sail Monday from the port of Wonsan where they had docked during the rare goodwill visit.

While in North Korea, the Chinese delegation, led by the commander of China's northern fleet, Vice Admiral Tian Zhong, visited North Korea's East Sea fleet and the Wonsan agricultural university. Chinese officers hosted by North Korean Rear Admiral Kim Myong Sik also laid flowers at the memorial of North Korea's founder Kim Il Sung.

Naval troops from both countries participated in sports games and other events.

China is North Korea's closest ally and aid donor.

Before their arrival in North Korea, the ships stopped at the Russian far-eastern city of Vladivostok, where they participated in celebrations marking the 315th anniversary of the Russian navy.