The secretary of state is the most senior US official to have met the North Korean leader and a key figure in preparations for next week's historic summit.

US President Donald Trump is due to meet Kim on June 12 in Singapore for a summit called to press Pyongyang to end its nuclear and long-range missile programs.

"He has indicated to me personally that he's prepared to denuclearize. That he understands that the current model doesn't work," Pompeo said.

"That he's prepared to denuclearize and that, too, he understands... that this has to be big and bold and we have to agree to making major changes."

Following the summit, Pompeo will fly on to China, Japan and South Korea to brief the key regional players on the next steps in the diplomatic effort.

"I will provide an update and underscore the importance of implementing all sanctions imposed on North Korea," Pompeo told reporters at the White House.