SEOUL (Reuters) - Chinese President Xi Jinping intends to visit North Korea next year after receiving an invite from North Korean leader Kim Jong Un, South Korea said on Saturday, which would make Xi the first Chinese leader to do so since 2005.

President of China Xi Jinping arrives for the APEC CEO Summit 2018 at Port Moresby, Papua New Guinea, 17 November 2018. Fazry Ismail/Pool via REUTERS

Xi told South Korean president Moon Jae-in in a bilateral meeting on the sidelines of the Asia Pacific Economic Co-operation (APEC) summit in Papua New Guinea that he would “make time” to visit North Korea next year.

Xi added that China would continue to play a constructive role in building peace on the Korean peninsula, Kim Eui-kyeom, spokesman for South Korea’s presidential office, said at a briefing after the meeting between Xi and Moon.

This comes at a time when negotiations between North Korea and the United States appear to have stalled over how to remove the Pyongyang’s nuclear weapons.

At an unprecedented summit in Singapore, U.S. President Donald Trump and North Korean leader Kim agreed in June to work toward denuclearization and peace on the Korean peninsula and establish new relations. But the agreement was short on specifics, and negotiations have made little headway since.

Xi’s trip to North Korea would be the first by a Chinese president since his predecessor Hu Jintao’s visit in 2005. Xi traveled to North Korea in 2008 as a vice president.

Amid existing international sanctions on North Korea following its weapons tests, China is Pyongyang’s sole major ally and a key economic lifeline for the isolated country.

China appears to have relaxed enforcement of sanctions on Pyongyang, as relations between China and North Korea have thawed after the long-time ally of Beijing began to engage with the United States this year, a U.S. congressional commission said earlier this week.

China’s account of the bilateral meeting in Papua New Guinea made no mention of Xi planning to go to North Korea.

Xi said that in the past year, the situation on the Korean Peninsula had undergone positive changes returning to the “correct track” of talks, according to a Chinese foreign ministry statement.

“At present, the situation on the peninsula is at a critical stage,” the ministry cited Xi as saying.

China and South Korea should strengthen communication and coordinate the process of promoting the denuclearization of the peninsula and establishing a peace mechanism, Xi said.

“The key is that the parties concerned meet each other half way, show flexibility, and are able to talk and for those talks to get results,” he said.

The two leaders agreed that a second summit between Washington and Pyongyang and a planned visit by North Korean leader Kim to Seoul would be an “important breakthrough” in resolving the situation on the peninsula, according to South Korea’s presidential office.

The South Korean presidential spokesman said Xi was also willing to come to South Korea next year at a convenient time.

South Korea’s presidential office issued a transcript of its briefing on the meeting in Port Moresby.