SEOUL, April 27 - Smiling and holding hands, North Korean leader Kim Jong Un and South Korean President Moon Jae-in met at the heavily fortified demilitarised zone between the countries on Friday in the first summit for the two Koreas in over a decade.

The meeting, aimed at ending their decades-long conflict and easing tensions over the North's nuclear weapons programme, comes weeks before Kim is due to meet U.S. President Donald Trump.

Moon greeted Kim at the military demarcation line at 9:30 a.m. (0030 GMT), making Kim the first North Korean leader to set foot in the South since the 1950-53 Korean War.

In an unplanned move, Kim invited Moon to step briefly across the demarcation line into North Korea, before the two leaders crossed back into South Korea holding hands.

South Korean President Moon Jae-in and North Korean leader Kim Jong Un meet in the truce village of Panmunjom inside the demilitarized zone separating the two Koreas, South Korea, April 27, 2018. Photo: Reuters

The two were handed flowers by a South Korean boy and girl, residents of a village situated in the demilitarised zone.

Walking on a red carpet rolled out for the two heads of state, the pair were met by a South Korean honour guard in historical costumes and playing traditional music.

Kim wore glasses and his trademark black Mao suit, while the rest of the North Korean delegation appeared in military uniforms or Western attire.

Kim stopped to sign a guest book in the South's Peace House before the two leaders met for a private discussion.

"A new history starts now. An age of peace, from the starting point of history," Kim wrote in Korean in the book, dating and signing the entry.

Moon and Kim are expected to talk denuclearisation and exchanges between the Koreas and also will plant a memorial tree at the border truce village of Panmunjom.

The United States is hopeful talks between Kim and Moon will make progress on achieving peace and prosperity, the White House said in a statement as the two men began their summit.

The White House also said it looks forward to continuing discussions with South Korea in preparation for the planned meeting of Trump and Kim in the coming weeks.

South Korean President Moon Jae-in and North Korean leader Kim Jong Un arrive at the Peace House in the truce village of Panmunjom inside the demilitarized zone separating the two Koreas, South Korea, April 27, 2018. Photo: Reuters

Just months ago, Trump and Kim were trading threats and insults as North Korea's rapid advances in pursuit of nuclear-armed missiles capable of hitting the United States raised fears of a fresh conflict on the Korean peninsula.

Earlier Friday, North Korea's official KCNA news agency said Kim would "open-heartedly discuss with Moon Jae-in all the issues arising in improving inter-Korean relations and achieving peace, prosperity and reunification of the Korean peninsula."

Just days before the summit, Kim said North Korea would suspend nuclear and long-range missile tests and dismantle its only known nuclear test site.

Moon travelled to the meeting in a large motorcade, stopping briefly to greet dozens of summit supporters waving South Korean flags near the Blue House.

Hundreds of demonstrators were seen gathering in downtown Seoul from early morning to protest or support the summit.

Scepticism has been rampant about whether Kim is ready to abandon the hard-earned nuclear arsenal his country has defended and developed for decades as what it says is a necessary deterrent against U.S. invasion.

The two neighbours expect to release a joint statement late on Friday - possibly called the Panmunjom Declaration - that could address denuclearisation and peace, and an improvement in relations, South Korean officials said.

South Korean President Moon Jae-in and North Korean leader Kim Jong Un meet in the truce village of Panmunjom inside the demilitarized zone separating the two Koreas, South Korea, April 27, 2018. Photo: Reuters

Kim and Trump are expected to meet in late May or June, with Trump saying on Thursday he was considering several possible dates and venues.

The White House released two photographs of then Secretary of State-designate and CIA chief Mike Pompeo's meeting with Kim in North Korea over the Easter weekend to discuss the planned summit. It was Kim's first known meeting with a U.S. official.

The photos show Kim and Pompeo, who was confirmed as secretary of state on Thursday, shaking hands. In one they faced each other looking serious; in the other they both appeared to wear faint smiles.

The latest summit has particular significance not least because of its venue: the Demilitarised Zone, a 160-mile (260-km) long, 2.5-mile (4-km) wide strip of land created in the 1953 armistice to serve as a buffer between the South and North.

For the first time, key moments such as Kim crossing the border into the South, the two leaders shaking hands and walking to the Peace House for their talks, were broadcast live.

Besides capturing the two leaders' candid interactions, the live feed broadcast a few hiccups, including when a key photo op blocked was blocked by a photographer's backside.