North Korea denounced US Secretary of State Mike Pompeo as an obstruction to nuclear negotiations on Wednesday, days before President Donald Trump visits Seoul while talks with Pyongyang are deadlocked.
The process has been stalled since a second summit between Trump and North Korean leader Kim Jong Un in Hanoi in February collapsed, after they failed to agree on what the North would be willing to give up in exchange for sanctions relief.
The two sides have had minimal contact and Trump is due to fly to Seoul at the weekend for talks with South Korean President Moon Jae-in.
But a spokesman for the North's foreign ministry criticised Trump's top diplomat 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 per cent of the North Korean economy is sanctioned."