SEOUL, Sept. 10 -- The South Korean government acknowledged Thursday that it extracted a small amount of plutonium during a 1982 research experiment, a declaration that came a week after the country acknowledged its scientists had secretly enriched uranium.
Diplomats at the International Atomic Energy Agency in Vienna said the agency had begun to suspect that South Korea was conducting nuclear experiments more than six years ago and said South Korean officials had worked hard to hide the experiments from inspectors.
Workers dismantle the facilities of a research reactor in Seoul. The IAEA said South Korea tried to hide nuclear tests from international inspectors.
(Kang Chang-kwang -- AP)
"They had a fairly elaborate plan involving denial and deception in order to evade detection by inspectors," said one diplomat who would discuss the agency's investigation only on condition of anonymity.
South Korean Foreign Ministry officials called those accusations "groundless and unsubstantiated" and said they had fully cooperated with inspectors and would continue to do so.
In Washington, U.S. officials said they gave a clear message to South Korea this week that they consider the charges to be serious and would apply the same standards to any country found to be violating the nuclear Non-Proliferation Treaty.
That message, which diplomats said would be repeated next week in Vienna at a board meeting of the IAEA, was meant to assuage concerns that the United States was applying a double standard by pushing for tough action against North Korea and Iran, which have also been accused of conducting clandestine nuclear work.
The IAEA believes that South Korea's work on plutonium and uranium -- the key ingredients for nuclear weapons -- seriously violated the treaty and that the matter could be referred to the U.N. Security Council in November, diplomats said.
One diplomat familiar with the IAEA's work said that despite South Korea's official denials, uranium was secretly enriched in 2000 to nearly bomb-grade levels and the other experiment was optimized to produce bomb-grade plutonium. On Friday, South Korean officials again disputed that their experiments had reached anywhere near bomb-grade levels.
South Korea, which derives 40 percent of its energy from nuclear power, contends that all the tests were one-time research efforts unrelated to weapons programs.
The IAEA announced last week that it had launched an intensive investigation after South Korea belatedly admitted to enriching a small amount of uranium during three experiments in January and February of 2000 -- tests that diplomats and experts said the South Korean government was required to report under terms of the Non-Proliferation Treaty.
North Korea, which has been pressured by the United States about its nuclear program, reacted quickly to the report on South Korea. On Wednesday, North Korea's ambassador to the United Nations, Han Sung Ryol, said the Bush administration had a "double standard" on the Korean Peninsula and warned of a budding "nuclear arms race" in northeast Asia.
North Korea expelled international inspectors and withdrew from the Non-Proliferation Treaty about two years ago, and U.S. intelligence officials have said they believe the North Koreans have now amassed an arsenal of up to eight nuclear devices. After three rounds of six-nation talks on the North Korean nuclear program in Beijing, the Pyongyang government and the Bush administration have not significantly changed their negotiating positions. Analysts are concerned about progress in the talks, predicting they may be delayed until after the U.S. presidential election in November.
"This gives another reason for North Korea to raise the issue of fairness with the international community," said Jhe Sung Ho, professor of law at Joongang University in Seoul. "They are going to claim that Washington is pressing them while giving South Korea a break."
South Korea conducted nuclear weapons research during the 1970s but is believed to have abandoned it under U.S. pressure before the end of the decade. One South Korean official familiar with the government's report to the IAEA on the 1982 plutonium experiment said details of the test remained sketchy but insisted there was no indication it had been related to a weapons program.