North Korea is willing to hold talks with the United States on denuclearisation and will suspend nuclear tests while those talks are under way, the South says.

A South Korean delegation has just returned from the North where it met leader Kim Jong Un.

North and South Korea, still technically at war but enjoying a sharp easing in tension since the Winter Olympics in the South last month, will also hold their first summit in more than a decade next month at the border village of Panmunjom, the head of the delegation, Chung Eui-yong, told a media briefing on Tuesday.

"North Korea made clear its willingness to denuclearise the Korean peninsula and the fact there is no reason for it to have a nuclear program if military threats against the North are resolved and its regime is secure," Chung said.

He also cited the North as saying it would not carry out nuclear or missile tests while talks with the US were under way. North Korea has not carried out any such tests since November last year.

Washington and Pyongyang have been at loggerheads for months over the North's nuclear and missile programs, with US President Donald Trump and Kim Jong Un trading insults and threatening war. North Korea has regularly vowed never to give up its nuclear program, which it sees as an essential deterrent against US plans for invasion.

The US, which stations 28,500 troops in the South, a legacy of the Korean War, denies any such plans.

To ensure close communication, the two Koreas, whose 1950-53 conflict ended in a mere truce, not a peace treaty, will set up a hotline between South Korean President Moon Jae-in and Kim Jong Un, Chung said.

The last inter-Korean summit was in 2007 when late former president Roh Moo-hyun was in office.

The agreement came on the heels of a visit made by a 10-member South Korean delegation led by Chung to the North Korean capital, Pyongyang, on Monday in hopes of encouraging North Korea and the US to talk to one another.

The South's delegation leader, Chung, said he would travel to the US to explain the outcome of the visit to North Korea and that he had a message from North Korea he will deliver to Trump.

Chung will later visit China and Russia, while Suh Hoon, the head of South Korea's spy agency and another member of the delegation, will head to Japan.