SEOUL — North Korean leader Kim Jong-un has visited China at the invitation of President Xi Jinping and reaffirmed his commitment to denuclearisation during their first summit, the two countries’ media said Wednesday.

The North’s leader made a surprise "unofficial" visit to China from Sunday to Wednesday, accompanied by his wife Ri Sol-ju and key officials, including de facto No. 2 figure Choe Ryong-hae, according to the North’s state news agency.

It was Kim’s first foreign trip since he took office in late 2011. Kim’s father, Kim Jong Il, visited China eight times during his tenure as North Korea’s supreme leader.

The summit came as Kim plans to meet the leaders of South Korea and the United States in the coming months.

His trip was seen as aimed at mending long-frayed ties with China, North Korea’s sole ally and key economic benefactor, which has joined international sanctions over the North’s nuclear and missile programmes.

By holding the meeting, Kim also appeared intent on securing diplomatic leverage ahead of talks with Seoul and Washington over North Korea’s nuclear programmes. Kim is set to hold summits with President Moon Jae-in in late April and is supposed to meet US President Donald Trump by May.

For China, the summit also seemed to offer a chance to highlight its role as a mediator in resolving North Korea’s nuclear and missile programmes.

The North’s leader told Xi that the situation on the Korean Peninsula is starting to "get better" as it has taken an initiative to ease tensions and propose for peace talks, according to China’s Xinhua News Agency.

"It is our consistent stance to be committed to denuclearisation on the peninsula," in accordance with the will of late founder Kim Il-sung and former leader Kim Jong-il, Kim was quoted as saying by the report.

Trump has agreed to meet with Kim after South Korean envoys relayed Kim’s expression of his commitment to denuclearisation.

North Korea’s leader also officially revealed his willingness to hold summits with the leaders of South Korea and the US, according to Xinhua, as US President Donald Trump has inserted hawkish officials to important foreign policy posts recently.

Kim said that North Korea’s denuclearisation is up to the South and the US.

"The issue of denuclearisation of the Korean Peninsula can be resolved, if South Korea and the U.S. respond to our efforts with goodwill, create an atmosphere of peace and stability while taking progressive and synchronous measures for the realisation of peace," he was quoted as saying by Xinhua.

Kim did not elaborate on what "progressive and synchronous" steps mean.

The North’s Korean Central News Agency reported that Kim invited Xi to Pyongyang at his convenient time and the Chinese leader accepted it.

During the summit, Xi expressed a "warm welcome" to Kim, saying that ties between Beijing and Pyongyang should be continuously developed.

Tensions between the North and the US heightened last year, amid North Korea’s advancement in its nuclear and missile programmes. Kim and Trump exchanged personal insults and bellicose rhetoric, raising fears about war on the divided peninsula.

It conducted its sixth and most powerful nuclear test in September last year. The North launched three intercontinental ballistic missiles (ICBMs) last year, which analysts say are capable of reaching the US mainland.

But the North extended a rare olive branch to Seoul in January, as Kim expressed his willingness to send athletes to the PyeongChang Winter Olympics held in the South last month.

The US has been carrying out its campaign for "maximum pressure" to make the North give up its nuclear arsenal and bring it to the negotiation table.

South Korea’s spy agency told lawmakers this week that the South plans to simultaneously seek to provide a security guarantee for North Korea and make the North give up its nuclear weapons when the two Koreas hold a summit.

Seoul’s unification ministry gave a positive assessment of signs of better ties between the North and China.

"Ahead of the North’s summits, we believe that an improvement in Pyongyang-Beijing relations will help resolve the North’s nuclear issue and bring peace to the Korean Peninsula," Baik Tae-hyun, spokesman at Seoul’s unification ministry, told a press briefing. — YONHAP