North Korea accused the United States on Thursday of pushing for worldwide sanctions despite goodwill moves by Pyongyang and said progress on denuclearization promises could not be expected if Washington continues to follow an "outdated acting script".
In an April summit, President Moon Jae-in and North Korean leader Kim Jong-un agreed to seek such declaration this year through three-way meetings involving the two Koreas and the United States or four-way talks involving the two Koreas, the USA and China.
Since the June meeting, Pyongyang has announced measures including halting missile and nuclear tests.
But there was no financial transaction made, which would constitute another violation of the United Nations sanctions, as the companies took coal in return for mediating trade between North Korea and Russia, Roh said.
The White House and US State Department did not immediately respond to requests for comment.
The latest statement by the North's foreign ministry also accused United States officials of "going against the intention of President Trump" by "making baseless allegations against us and making desperate attempts at intensifying the worldwide sanctions and pressure".
The unidentified spokesperson also warned that there is no guarantee that the hard-won atmosphere of stability on the Korean Peninsula will continue.
US National Security Advisor John Bolton has also weighed in on the issue, saying Sunday that nobody in Trump's administration is "starry-eyed" about the prospect "of North Korea actually denuclearising".
The North Korean government said in a statement through its mission to the United Nations that it has halted nuclear missile tests, dismantled a nuclear test site and begun to return the remains of Americans killed in the Korean War, but lamented continued criticism from US officials.
"The Americans utter attractive words when negotiating and promise a very bright future but they deliver on none of their commitments when it comes to action", Larijani said.
North Korea nevertheless went ahead with the return of the remains of USA soldiers killed in the 1950-53 Korean war, it said. South Korea's unification minister will lead the delegation from Seoul but North Korea, which proposed the Monday meeting first, did not confirm the makeup of its delegation.
The president has also repeatedly defended Kim's intentions, tweeting last month that he was "confident" the leader would "honor the contract we signed &, even more importantly, our handshake".
The Korean Peninsula is still technically in a state of war because the 1950-53 fighting ended with a ceasefire, not a peace treaty.
The summit held in Singapore marked the first time Kim Jong-un had met a western leader.