Kim Jong Un, top leader of the Democratic People's Republic of Korea (DPRK) promised to further develop his country's relationship with China, the country's official Korean Central News Agency (KCNA) reported on Wednesday.

Kim's latest pledge came in a letter sent to Chinese President Xi Jinping, who earlier sent a congratulatory message on the 72nd anniversary of the founding of the DPRK.

"Kim Jong Un in his message expressed heartfelt thanks on behalf of the Workers' Party of Korea and the government and all the people of the DPRK and on his own behalf to the general secretary for extending warm congratulations and best wishes on the occasion of the 72nd founding anniversary of the DPRK," the KCNA reported.

In the letter, Kim also expressed he willingness to do his best to develop the DPRK-China friendship into a new stage.