North Korea took a swipe at the United States on Thursday over its continued push for international sanctions, warning that progress toward Pyongyang's denuclearization could be in jeopardy.

North Korea's Foreign Ministry said in a statement, carried by the state-run Korean Central News Agency, that some high-level U.S. officials "are making baseless allegations against us and making desperate attempts at intensifying the international sanctions and pressure."

It said North Korea has halted testing of nuclear weapons and long-range missiles and dismantled its nuclear test site as "practical denuclearization steps" and returned the remains of some American soldiers killed in the 1950-1953 Korean War as a measure to build mutual confidence.

"We hoped that these goodwill measures would contribute to breaking down the high barrier of mistrust existing between the DPRK and the U.S. and to establishing mutual trust," it said, referring to North Korea by its formal name -- the Democratic People's Republic of Korea.

"As long as the U.S. denies even the basic decorum for its dialogue partner and clings to the outdated acting script which the previous administrations have all tried and failed, one cannot expect any progress" in implementing a joint statement issued by the two countries' leaders, including denuclearization, the ministry said.

Skepticism is mounting over North Korea's intention to take concrete measures toward denuclearization as its leader Kim Jong Un promised U.S. President Donald Trump at a historic summit in Singapore in June.

White House national security adviser John Bolton reiterated Tuesday that the United States will keep economic sanctions on North Korea in place until real progress is made toward dismantling the country's nuclear program.