North Korea (search) said Monday that it will not give up nuclear development in light of unauthorized nuclear experiments by South Korea (search), where U.N. inspectors nuclear inspectors were conducting an investigation.

Rodong Sinmun, an official North Korean newspaper, said in an editorial that the secret nuclear activities in South Korea in 1982 and 2000 were an "inevitable result of double standards" applied by the United States, the South's chief ally.

The comments, which echoed other North Korean statements in recent days, were another blow to troubled efforts to hold another round of talks aimed at persuading North Korea to end its nuclear weapons development. Last Thursday, North Korea said it would not attend planned six-party talks on its nuclear activities until South Korea fully discloses the details of its secret atomic experiments.

"South Korea's uranium experiment is evidence that the United States is trying to take advantage of the six-party talks to disarm North Korea rather than keep the Korean Peninsula free of nuclear weapons," said Rodong Sinmun. The editorial was reported by South Korea's national news agency Yonhap.

Three rounds of six-party talks have been held in Beijing, but negotiators have made little progress. The participants are the two Koreas, Japan, China, Russia and the United States.

South Korea acknowledged this month that it extracted a small amount of plutonium in an experiment more than 20 years ago. That admission came shortly after it said it conducted a uranium-enrichment experiment four years ago. Plutonium and enriched uranium are two key ingredients of nuclear weapons.

Seoul said the experiments were purely research, and not intended as preparation to make nuclear weapons. But it acknowledged it should have revealed details to the U.N. nuclear agency in Vienna, the International Atomic Energy Agency.

"It is apparent that we cannot give up our nuclear program as the United States is trying to cover up the South's secret nuclear activities," Rodong Sinmun said.

"Our stance that we cannot give up nuclear development is definitely justifiable," the newspaper said. North Korea says it has a nuclear "deterrent," and international experts suspect it already has several nuclear weapons.

On Sunday, a delegation from the International Atomic Energy Agency arrived in South Korea for a follow-up probe into the country's secret nuclear experiments. On Monday, the five-member team visited the Korea Atomic Energy Research Institute in Daejeon, 125 miles south of Seoul.