The new Chinese ambassador to North Korea, Li Jinjun, has pledged to spare no efforts to warm relations with the unruly ally, saying he aims to "blaze a new trail" in promoting the tradition of their friendly relations.

The 59-year-old Li, former vice minister of the Chinese Communist Party's International Department that has been closely engaged with North Korea's ruling party, took up the post last week amid strained political ties between the two nations because of Pyongyang's defiant pursuit of nuclear weapons.

"As new ambassador to North Korea, I am responsible for this glorious mission," Li said in a March 20-dated statement posted by the Chinese Embassy in Pyongyang.

Li said he will "actively blaze a new trail in the mission of promoting the development of China-North Korea relations and contributing to maintain peace and stability on the (Korean) peninsula."

Bilateral relations between North Korea and China, which jointly fought against South Korea, the United States and 20 other allies during the 1950-53 Korean War, were once touted as close as "lips and teeth."

But the current Chinese Communist Party leadership led by President Xi Jinping has been increasingly frustrated by North Korea's unruly behavior, including its third nuclear test in early 2013. 

Developing the traditional friendship between North Korea and China is an "unswerving policy" of China's ruling Communist Party, Li said, repeating China's policy stance on North Korea.

North Korean leader Kim Jong-un has yet to visit China since taking the helm of the reclusive state in late 2011. Kim is likely to visit Russia in May in what would be his international debut and an apparent message of affront against China. (Yonhap)