North Korean leader Kim Jong Un visits the Command of the Strategic Force of the Korean People's Army (KPA) in an unknown location in North Korea in this undated photo released by North Korea's Korean Central News Agency (KCNA) on August 15, 2017.

North Korea on Friday ruled out negotiations with Washington as long as joint U.S-South Korea military exercises continue, and said that Pyongyang's atomic weapons program would remain as a deterrent against a U.S. nuclear threat.

In an interview with Reuters, Han Tae Song, North Korea's ambassador to the United Nations in Geneva, brushed off the new sanctions which the Trump administration has said it is preparing, as well as the possibility of North Korea being added to a U.S. list of states sponsoring terrorism.

South Korea and the United States agreed on Friday to keep working for a peaceful end to the North Korean nuclear crisis, but a U.S. envoy said it was difficult to gauge the reclusive North's intentions as there has been "no signal."

Han, asked about those bilateral talks in Seoul, replied: "As long as there is continuous hostile policy against my country by the U.S. and as long as there are continued war games at our doorstep, then there will not be negotiations."

"There are continued military exercises using nuclear assets as well as aircraft carriers, and strategic bombers and then...raising such kinds of military exercises against my country," he said.

He, who is ambassador to the U.N.'s Conference on Disarmament, was speaking at the Democratic People's Republic of Korea (DPRK) mission in Geneva, where the DPRK and the United States secured a 1994 nuclear deal which later fell apart.

He said he had no information on when North Korea might test a ballistic missile again, after the last one two months ago.

"The DPRK, my country, will continue to build-up its self-defense capability, the pivot of which is nuclear forces and capability for a triumphant...strike as long as U.S. and hostile forces keep up nuclear threat and blackmail," Han said.

"Our country plans ultimate completion of the nuclear force," he said.