Image copyright DigitalGlobe Image caption A satellite image of the Punggye-ri nuclear test site in North Korea
North Korea's nuclear test site will close in May, the South Korean president's office has said.
A spokesman said the closure of the Punggye-ri site would be done in public and foreign experts from South Korea and the US would be invited to watch.
Scientists have said the site may have partially collapsed in September.
On Friday, North Korean leader Kim Jong-un and South Korea's President Moon Jae-in agreed to work to rid the Korean peninsula of nuclear weapons.
Their summit came after months of warlike rhetoric from the North.
On Saturday, US President Donald Trump said he would likely hold talks with the North Korean leadership "over the next three or four weeks" about the denuclearisation of the peninsula.
Presidential spokesman Yoon Young-chan said that Mr Kim had stated he "would carry out the closing of the nuclear test site in May".
Mr Yoon added that the North Korean leader had also said he "would soon invite experts of South Korea and the US to disclose the process to the international community with transparency".
The office also said North Korea would change its time zone - currently half an hour different - to match that of the South.
North Korea has so far made no public comments on the issue.
What is known about the test site?
Situated in mountainous terrain in the north-east, it is thought to be the North's main nuclear facility.
The nuclear tests have taken place in a system of tunnels dug below Mount Mantap, near the Punggye-ri site.
Six nuclear tests have been carried out there since 2006.
After the last, in September 2017, a series of aftershocks hit the site, which seismologists believe collapsed part of the mountain's interior.
Mr Kim made an apparent reference to these reports, according to South Korea's Yonhap news agency.
"Some say that we are terminating facilities that are not functioning, but you will see that they are in good condition," the North Korean leader was quoted as saying by Mr Yoon on Sunday.
The information about the nuclear site has been gathered mainly from satellite imagery and tracking the movement of equipment at the location.
Analysis by the BBC's Korea correspondent Laura Bicker
This is another significant and symbolic step by Kim Jong-un.
He had already announced he'd be closing the Punggye-ri test site, but now he has told officials in South Korea that he's prepared to make it public and invite experts and media from Seoul and the US to inspect it.
Mr Kim also told President Moon that he hoped trust could be built with the US and reiterated that there would be no need for him to have nuclear weapons if they formally ended the war on the Korean peninsula.
Mr Kim said once Washington spoke to him North Korea would know he was not an aggressor.
He added that his heart was broken when he saw the two clocks with different Korean time zones hanging on the wall of the peace house at the border between the two countries.
He will now match the time zone in the North with that of the South.
What was agreed at the inter-Korean summit?
Mr Kim and Mr Moon said they would pursue talks with the US and China to formally end the Korean War, which ended in 1953 with a truce, not total peace.
Media playback is unsupported on your device Media caption Kim Jong-un issues his pledge for peace with South Korea
The commitment to denuclearisation does not explicitly refer to North Korea halting its nuclear activities but rather to the aim of "a nuclear-free Korean peninsula".
The statement talks about this taking place in a phased manner, but does not include further details.
Many analysts remain sceptical about the North's apparent enthusiasm for engagement.
Previous inter-Korean agreements have been abandoned after the North resorted to nuclear and missile tests and the South elected more conservative presidents.
Mr Kim said the two leaders had agreed to work to prevent a repeat of the region's "unfortunate history" in which progress had "fizzled out".
Other points the leaders agreed on in a joint statement were:
soyfox on April 29th, 2018 at 03:42 UTC »
Just my own quick translation of the press release regarding the matching time zones: "During the north-south summit, Kim saw 2 clocks in the waiting room, each showing seoul time and pyongyang time. He say that was sad to see, and thus will change the times to match seoul time. Even tough there will be lots of administrative difficulties with the change, the north will initiate the change because it was they who changed it from the original seoul time."
also another interesting sentence : Kim had said "If you talk with me, you'll know that i'm not the type of person to launch missiles to the south or across the pacific. If a peace and non-agression agreement is made, why would we continue to hold onto the nukes and live so difficultly."
Just want to mention that any korean speaker would agree that kim has some serious speaking skills. Whatever you think of that guy, his speeches at the summit were eloquent
yh5203 on April 29th, 2018 at 03:38 UTC »
Full Text of the Blue House announcement.
Speaker: Yoon Young-chan, Senior Secretary to the President for Public Communication
There are two things to announce today.
First, Public disclosure of the closing of North Korean nuclear test facility
North Korea's chairman Kim Jong Un, at the inter-Korean summit with president Moon held on 27th at the Southern side of Panmunjom's Peace House, has said that Northern nuclear test facility will be closed in May and that to transparently disclose it to the international community the S.Korean and American experts and media will be invited to N.Korea soon. Chairman Kim expressed this at the morning session of the summit with president Moon and said, "Some say that we are closing the ones that are unusable. They will know when they come and see that we have two bigger tunnels than the current test facilities and they are very much intact."
President Moon has immediately welcomed chairman Kim's plan to disclose N.Korean nuclear test facilities and the both leaders have agreed to decide on the timing of the inviting the S.Korean and the US experts and media as soon as N.Korea is ready.
Chairman Kim's announcement of plans to close the nuclear test facilities and disclose the closure is an expression of his will to proactively engage the soon to follow discussion on verifying N.Korean nukes.
Chairman Kim also said, "Though the US has an innate dislike of N.Korea, once they talk with us, they will know that I'm not the kind of person to launch nuke towards the South or over the Pacific or target the US. If we meet often in the future and build trust with the US and if the end of war and non-aggression is promised, then why would we live in difficulty with the nukes?"
Chairman Kim continued, "We will not repeat the painful history of the Korean war. There must not be another instance of spilling blood on our common land of our people. I affirm that there will never be the using of violence."
Chairman Kim said that there needs to be an effective measure to systematically manage and prevent an accidental military clashes or the risk of expanding to a war which are the problem.
Second, Unifying Pyongyang standard time to Seoul standard time.
Chairman Kim expressed his position to fit Pyongyang standard time to Seoul standard time, which is 30 minutes behind. In the afternoon of the 27th at the talks between the leaders and their first ladies, Chairman Kim has said, "In the reception room of the Peace House there were two clocks. One pointed at the Seoul time and the other pointed at Pyongyang's. Seeing this, I was very saddened. Let's unite the inter-Korean time first." Chairman Kim said, "We have changed the time standard that we used to share, so we will return to how it was. You may disclose this publicly."
Uniting the standard time is a difficult measure that carries many administrative difficulties and cost within N.Korea. The fact that chairman Kim has decided thus carries significance that they are stepping up actively to join the international community and it was a decision to remove the obstacles on the path to inter-Korean and NK-US exchange and cooperation that are to come.
Pisforpotato on April 29th, 2018 at 02:55 UTC »
Sounds like they had a "fuck you we're different" time zone.