North Korea's foreign minister told the United Nations on Saturday continued sanctions were deepening its mistrust in the United States and there was no way the country would give up its nuclear weapons unilaterally under such circumstances.

Ri Yong Ho told the world body's annual General Assembly that North Korea had taken "significant goodwill measures" in the past year, such as stopping nuclear and missiles tests, dismantling the nuclear test site, and pledging not to proliferate nuclear weapons and nuclear technology.

"However, we do not see any corresponding response from the US," he said.

"Without any trust in the US there will be no confidence in our national security and under such circumstances there is no way we will unilaterally disarm ourselves first."

While Ri reprised familiar North Korean complaints about Washington's resistance to a "phased" approach to denuclearisation under which North Korea would be rewarded as it took gradual steps, his statement appeared significant in that it did not reject unilateral denuclearisation out of hand as Pyongyang has done in the past.

Ri referred to a joint statement issued by Kim Jong Un and Donald Trump at a first ever summit between a serving US president and a North Korean leader in Singapore on June 12, when Kim pledged to work toward "denuclearisation of the Korean peninsula" while Trump promised guarantees of North Korea's security.

North Korea has been seeking a formal end to the 1950-53 Korea War, but the United States has said Pyongyang must give up its nuclear weapons first. Washington has also resisted calls to relax tough international sanctions on North Korea.

"The US insists on the 'denuclearisation-first' and increases the level of pressure by sanctions to achieve their purpose in a coercive manner, and even objecting to the 'declaration of the end of war,'" Ri said.

"The perception that sanctions can bring us on our knees is a pipe dream of the people who are ignorant about us. But the problem is that the continued sanctions are deepening our mistrust."

Ri made no mention of plans for a second summit between Kim and Trump that the US leader highlighted at the United Nations earlier in the week.

The minister instead highlighted three meetings between Kim and South Korean leader Moon Jae-in in the past five months and added: "If the party to this issue of denuclearisation were South Korea and not the US, the denuclearisation of the Korean peninsula would not have come to such a deadlock."