North Korean leader Kim Jong-un / AP-Yonhap

North Korean leader Kim Jong-un vowed to elevate relations with China to a new strategic point as he sent a congratulatory message to Chinese President Xi Jinping to mark the 100th anniversary of the Communist Party of China, state media said Thursday.

In an apparent reference to the deepening Sino-U.S. rivalry, Kim also said in the message that "hostile forces" are engaged in "vicious slander and all-round pressure" upon China, but they can "never check the on-going advance of the Chinese people," according to the Korean Central News Agency (KCNA).

"Despite the complicated international situation, the two parties and the two countries, with firm faith in the justice of the socialist and communist cause, accelerate their advance toward a brighter future, tiding over difficulties and ordeals by dint of their militant friendship and bonds of kinship," Kim was quoted as saying by the KCNA.

"The WPK, by its firm unity with the CPC, would raise the DPRK-China friendship to a new strategic point as required by the times and as desired by the peoples of the two countries, and powerfully encourage the socialist construction... to vigorously advance despite any change of the situation and challenges," he added.