Kim offers to visit Seoul 'any time if you invite me': South Korea

North Korea's leader Kim Jong Un (left) steps with South Korea's President Moon Jae-in across the Military Demarcation Line that divides their countries on Apr 27, 2018. (Photo: AFP)

Kim made the remarks as the men chatted ahead of their summit in the Demilitarised Zone that divides the Koreas, the official said.

According to the official, Moon told the visitor he could "show you scenes far better than this if you come to the Blue House", with Kim responding: "Really? I will go to the Blue House any time if you invite me."

Earlier, on the Military Demarcation Line that delineates the border, Moon asked him: "While you come to the South, when can I possibly go over there?"

After stepping over the line and becoming the first North Korean leader to set foot in the South since the end of the Korean War in 1953, Kim responded: "Why don't we just cross over now?" - prompting Moon's unscripted entry into Northern territory.

Later on, Kim said: "The border is not even that high. Wouldn't it disappear if many people keep walking across it?"

Scenes of Moon and Kim joking and walking together marked a striking contrast to last year's barrage of North Korean missile tests and its largest ever nuclear test that led to sweeping international sanctions and fears of a fresh conflict on the Korean peninsula.

The dramatic meeting, aimed at ending their decades-long conflict, comes weeks before Kim is due to meet US President Donald Trump to discuss denuclearising the Korean peninsula.

"We are at a starting line today, where a new history of peace, prosperity and inter-Korean relations is being written," Kim said before the two Korean leaders and top aides began talks at the border truce village of Panmunjom.

During their private meeting, Kim told Moon he came to the summit to end the history of conflict and joked he was sorry for keeping Moon up with his late night missile tests.

"I heard that you had early morning sleep disturbed many times because you had to attend the National Security Council meetings because of us," he said.

"I will make sure that your morning sleep won't be disturbed," he added, reiterating a pledge he made when Moon's envoys visited Pyongyang earlier this year.

After talks lasting more than an hour and a half behind closed doors, Kim was driven back to the North side just before noon in a black limousine flanked by guards who ran alongside. Crossing the border, the vehicle had to drive across a lawn, as there is not a road linking the two sides at that spot.

Moon expressed hopes that after their summit at Panmunjom, "our meetings will continue at Pyongyang, Seoul, Jeju island and Paektu mountain" - the island and mountain at the southern and northern ends of the Korean peninsula.

Last year the North carried out a series of missile launches, many of them in the early hours, and its sixth nuclear test, but Kim promised Moon there would be no more.