South Korean President Moon Jae-in on Wednesday dismissed the idea that nuclear negotiations between Pyongyang and Washington had stalemated but stressed patience was needed to bridge a 70-year "sea of mistrust."

In written answers to questions submitted by leading media, Moon - who brokered talks between US President Donald Trump and North Korean leader Kim Jong-un last year - also urged Pyongyang to resume the dialogue to show its desire to denuclearize.

Moon is set to host the US leader this weekend as he tries to rekindle nuclear talks that have stalled since the second summit between Trump and Kim that ended without reaching an agreement in Hanoi in February.

"There is no reason to regard the current situation as a stalemate in the peace process on the peninsula just because the pace has remained slow," Moon said.

Trump and Kim's willingness to engage in dialogue had "never faded," he added in the interview with editors of major news agencies, noting a recent exchange of letters between them.

North Korea denounced US Secretary of State Mike Pompeo as an obstruction to nuclear negotiations on Wednesday.

A spokesman for North Korea's Foreign Ministry criticized Pompeo on Wednesday, calling recent comments by Pompeo a manifestation of the most extreme hostile acts against Pyongyang.

The top US diplomat told reporters this week the resumption of working-level talks with the North was becoming "a very real possibility," adding: "Some 80-plus percent of the North Korean economy is sanctioned."

He corrected himself, saying he had misspoken and the figure applied to the effect of US sanctions on Iran, but the remarks were nonetheless deemed reckless by Pyongyang.

"If the US sanctions are affecting 80-plus percent of our economy, as Pompeo mentioned, the question is whether the US target is to raise it up to 100 percent," the foreign ministry spokesman said in a statement carried by the North's official Korean Central News Agency (KCNA).

Moon said the implementation of agreements between the US and North Korea requires patience, given their long history of hostility.

"As their hostile relations have persisted for more than 70 years, it will be difficult to cross a sea of mistrust all at once," he added.

Hopes for a third summit between Kim and Trump appeared to be revived, CNN reported after Moon's comments.