US President Donald Trump has said he would "absolutely" be willing to talk on the phone to North Korean leader Kim Jong-un, and that he hopes a positive development results from talks between North Korea and South Korea.

North Korea agreed on Friday to hold official talks with South Korea next week, the first in more than two years, hours after Washington and Seoul delayed a military exercise amid a standoff over Pyongyang’s nuclear and missile programmes.

Mr Trump, answering questions from reporters at the presidential retreat at Camp David, expressed a willingness to talk to Mr Kim but not without preconditions.

"Absolutely, I would do that," he said. "I have no problem with that at all."

Mr Trump and Mr Kim have exchanged insults ever since the US president took office, with Mr Trump repeatedly calling the North Korean leader "rocket man" for testing nuclear weapons and ballistic missiles.

Earlier this week Mr Trump dismissed Mr Kim's taunt that the North Korean leader has a nuclear button on his desk, saying he has "a bigger button".

The talks between North Korea and South Korea are expected to cover the Winter Olympics, to be held in South Korea next month, and inter-Korean relations.

Mr Trump suggested the talks might lead to an easing of tensions and took credit for the diplomatic breakthrough, saying it was a result of his steady pressure.

"Look, right now they're talking Olympics. It's a start, it's [a] big start. If I weren't involved they wouldn't be talking at all right now," he said.

Mr Kim "knows I'm not messing around. I'm not messing around. Not even a little bit, not even one percent. He understands that," said Mr Trump.

"If something can come out of those talks, that would be a great thing for all of humanity, that would be a great thing for the world," he said.

North Korea has today announced a list of five officials who will represent Pyongyang, a day after South Korea confirmed its representatives, the South Korean unification ministry said.

The North Korean delegation will be led by Ri Son Gwon, head of the Committee for the Peaceful Reunification of the Fatherland that is usually tasked with dealing with South Korean affairs.