North Korean leader Kim Jong-un has sent a letter to Chinese President Xi Jinping on his 70th birthday, saying that Beijing's national power has "remarkably" strengthened under his leadership, Pyongyang's state media reported Thursday.

In the message, Kim said that Beijing has "built a comprehensively well-off society" and that its "national power and international position remarkably strengthened" under Xi's "energetic" leadership, according to the official Korean Central News Agency.

"The message expressed belief that the struggle for the prosperity of China will surely emerge victorious as there are the leadership of Xi Jinping and the Chinese party and people rallied around the Party Central Committee with him as its core," the KCNA said in an English-language dispatch.

The message came as the North has been seeking to strengthen ties with China, its traditional ally and economic benefactor, amid global sanctions on its nuclear and missile programs, and stalled denuclearization talks with the United States. (Yonhap)