North Korean leader Kim Jong Un pledged to close the country's nuclear test site in May, South Korean President Moon Jae-in's office said on Sunday.

Kim made the comment during Friday's historic summit with Moon, a spokesman for the South Korean president said.

He added that Kim had promised to invite US and South Korean experts and journalists to watch the closure, in the interests of transparency.

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Agreement signed

During Friday's landmark talks, the two leaders signed an agreement to pursue a nuclear-free peninsula and an official end to the Korean War.

No peace treaty was ever signed following the 1950-53 conflict between the two neighbors.

The North's pledge to close the test site follows a claim by two Chinese scientists last week that the facility, at Punggye-ri in the northwest of the country, had collapsed following the most recent nuclear test. US intelligence officials have since said they believe the site is still usable.

In its statement on Sunday, Seoul said that Pyongyang also plans to readjust its time zone to match the South's. In 2015, the North created its own "Pyongyang Time," 30 minutes behind the South.

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Just a few hours before Seoul's latest remarks, US President Donald Trump told a campaign rally in Michigan that he planned to meet Kim "in the next three, four weeks."

"Whatever happens, happens," he told supporters. "Look, I may go in. It may not work out. I leave."

Singapore likely

A senior US official has said Singapore and Mongolia were being considered as possible venues for the Trump-Kim summit.

Trump had a 75-minute phone call with South Korea's Moon on Saturday, which the US president described as "a long and very good talk."

The two leaders agreed that "unprecedented pressure" applied by the United States, South Korea and the international community had led to what they termed "this significant moment," according to a White House statement.

Trump said he also spoke to Japanese Prime Minister Shinzo Abe "to inform him of the ongoing negotiations."

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New US Secretary of State Mike Pompeo, meanwhile, reaffirmed that the North Korean leader is serious about getting rid of his country's nuclear weapons.

Kim is "prepared to ... lay out a map that would help us achieve" denuclearization, Pompeo told ABC News This Week with George Stephanopoulos.

He said the Trump administration's objective is "complete, verifiable, irreversible denuclearization."

North Koreans informed

After initially staying silent following the inter-Korean summit, North Korea's state media on Saturday lauded the meeting as a turning point for the peninsula, releasing the joint statement signed by Kim and Moon as part of a multi-page spread with more than 60 photos from the visit.

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"At the talks both sides had a candid and open-hearted exchange of views on the matters of mutual concern including the issues of improving the North-South relations, ensuring peace on the Korean Peninsula and the denuclearization of the peninsula," KCNA said.

It added that the night wrapped up with a dinner that had an "amicable atmosphere overflowing with feelings of blood relatives."

The North's de-escalation follows last year's soaring tensions which saw Kim and Trump trade personal insults and threats of war in response to Pyongyang's sixth nuclear test, by far its most powerful to date.

It also launched missiles capable of reaching the US mainland, prompting an international outcry and new, harsher sanctions against the isolated state.

mm/sms (AFP, AP, dpa, Reuters)