Li's visit came as the neighbours seek to maintain a close relationship despite periods of strained ties between China and North Korea over Pyongyang's nuclear programme.

Kim praised Li's visit as "showing the invariable support and special friendly feeling towards the WPK and the government and people of the DPRK" as well as Beijing's efforts to maintain "traditional DPRK-China friendly and cooperative relations and further develop them", state news agency KCNA reported.

Li stressed that "maintaining, consolidating and developing the traditional friendly and cooperative relations between the two countries is China's unwavering policy," according to China's state news agency Xinhua.

The celebrations came as North Korea's leader has been emboldened by the war in Ukraine, securing critical support from Russia after sending thousands of North Korean troops to fight alongside Moscow's forces.

Last month, Kim appeared alongside Chinese President Xi Jinping and Russian leader Vladimir Putin at an elaborate military parade in Beijing.