BEIJING (Reuters) - China appreciates North Korea’s “important efforts” to ease tension on the Korean peninsula, senior Chinese diplomat Wang Yi told the North’s foreign minister on Tuesday, hours after he called on all sides to stay focused on talks.

FILE PHOTO: China's State Councilor and Foreign Minister Wang Yi attends a news conference after a meeting with Vietnam's Deputy Prime Minister and Foreign Minister Pham Binh Minh (not pictured) at the Government Guesthouse in Hanoi, Vietnam April 1, 2018. REUTERS/Kham

China has traditionally been secretive North Korea’s closest ally, though ties had been frayed by North Korean leader Kim Jong Un’s pursuit of nuclear weapons and missiles and Beijing’s backing of tough U.N. sanctions in response.

But in late March Beijing vowed to uphold its friendship with its isolated neighbor and won a pledge from Kim to denuclearize the peninsula during a meeting with President Xi Jinping.

China’s Foreign Ministry gave only hours notice that Wang, a State Councillor and China’s Foreign Minister, would meet North Korean Foreign Minister Ri Yong Ho.

Wang told Ri that Xi and Kim had reached an important consensus on achieving a peaceful resolution to the peninsula nuclear issue during Kim’s visit to Beijing, his first known trip outside North Korea since he assumed power in 2011.

“China appreciates North Korea’s position working toward denuclearization of the peninsula and its important efforts to ease the situation on the peninsula, and supports meetings between the leaders of the North and South and between the North and the United States,” Wang said, according to a Chinese Foreign Ministry statement.

The ministry cited Ri as saying that North Korea would “maintain close strategic communications” with China on peninsula-related issues, and that the Kim-Xi meeting was an “important juncture” in the development of bilateral relations.

North Korea’s official news agency KCNA had said that a delegation headed by Ri left on Tuesday to meet other foreign ministers in Azerbaijan and to visit Russia, but made no mention of China.

“DISRUPTIVE FACTORS”

Earlier in the day, Wang said during a joint news briefing with visiting Swiss Foreign Minister Ignazio Cassis that he hoped a planned meeting in May between Kim and U.S. President Donald Trump would “increase mutual understanding”.

“But historical experience tells us that at the moment of easing of the situation on the peninsula and as first light dawns on peace and dialogue, frequently all manner of disruptive factors emerge,” Wang said.

“So we call on all sides to maintain focus, eliminate interference, and firmly follow the correct path of dialogue and negotiation.”

Cassis said that he would discuss with Wang the role that Switzerland could play in the strategic meetings between Kim and “some important partners on the international level”, but he did not elaborate.

A time and place have not been set for the Trump-Kim meeting to discuss denuclearization. North and South Korea will hold their first summit in more than a decade on April 27, South Korea has said.

Kim’s predecessors, grandfather Kim Il Sung and father Kim Jong Il, both promised not to pursue nuclear weapons but secretly maintained programs to develop them, culminating in the North’s first nuclear test in 2006 under Kim Jong Il.

North Korea has said in previous, failed talks aimed at dismantling its nuclear programme that it could consider giving up its arsenal if the United States removed its troops from South Korea and withdrew its so-called nuclear umbrella of deterrence from South Korea and Japan.

Some analysts have said Trump’s willingness to meet Kim handed Pyongyang a diplomatic win, as the United States had insisted for years that any such summit be preceded by North Korean steps to denuclearize.

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China had largely sat on the sidelines as North Korea improved relations with South Korea, raising worries in Beijing that it was no longer a central player in the North Korean issue.

The two Koreas have seen a significant thaw in ties since the North’s participation in the South’s Winter Olympics in February.

Kim Jong Un and his wife on Sunday made a surprise appearance at the first of two concerts performed by a South Korean art troupe this week in Pyongyang, titled “Spring is Coming”.

Kim proposed another concert in South Korea later this year with performers from the North in response to this week’s shows in Pyongyang by K-pop artists, South Korea’s Culture Minister Do Jong-whan told reporters in Seoul.

It was the first time a North Korean leader had attended a South Korean performance in the capital.