North Korea has sent a top military official to China as a personal envoy of leader Kim Jong-Un, at a time of strained relations between Pyongyang and its allies in Beijing, state media reported.
Choe Ryong-Hae, the director of the Korean People's Army politburo, flew to China on Wednesday, the Korean Central News Agency said, highlighting his role "as a special envoy" of the North's young leader.
Choe is believed to be the highest ranking North Korean official to visit China since late leader Kim Jong-Il in August 2011. Kim Jong-Un has never visited since he took over after his father's death in December 2011.
The trip comes at a sensitive time for North Korea-China relations which have been sorely tested in recent months by Pyongyang's refusal to heed Beijing's warnings over its nuclear weapons programme.
China has long been the impoverished, isolated North's sole major ally and chief economic benefactor, but Beijing sided with the rest of UN Security Council in imposing sanctions after the North's long-range rocket test in December last year, and its nuclear test in February.
The sanctions triggered a dangerous cycle of escalating military tensions on the Korean peninsula, during which China came under enormous US-led pressure to rein in its wayward ally which was threatening nuclear strikes against the US and South Korea.
Professor Yang Moo-Jin of the University of North Korean Studies in Seoul said the timing of Choe's visit was significant ahead of a scheduled June 7-8 summit between US President Barack Obama and China's new leader Xi Jinping.
"Choe is Kim Jong-Un's closest confidante, so Kim is sending his highest possible envoy to China ahead of the summit," Yang told AFP.
"This will be Kim's way to deliver his message to Obama concerning peace on the Korean peninsula and the nuclear issue," he added.
At the same time, a publicised visit by a figure of Choe's stature may be an effort to repair some of the damage done to a relationship that has weakened significantly since it was forged in the 1950-53 Korean War.
In line with the UN sanctions, Beijing has moved to tighten Pyongyang's financial operations in China which the international community says are the major conduit for funding its nuclear weapons programme.
The strain in relations was reflected most recently when a Chinese fishing boat with 16 crew was seized in waters between the two countries.
The boat's owner said the crew had been kidnapped by the North Korean military and a ransom demanded.
The crew was released on Tuesday, with China demanding an explanation for the incident.
The detention caused outrage online in China, with Internet users calling on Beijing to take a tough stance against Pyongyang, and accusing Chinese authorities of not trying hard enough to secure the men's release.
In an editorial Tuesday before the release was announced, the state-run Global Times, which often reflects nationalist opinion, said Beijing "should let the North Korean side know we are angry".