SEOUL, South Korea -- North Korea accused the United States of applying a double standard on the Korean Peninsula and warned Wednesday of a nuclear arms race in Northeast Asia following the revelation that South Korean scientists enriched a tiny amount of uranium in 2000.
The controversy over the South Korean experiment threatened to further disrupt troubled efforts to persuade North Korea to dismantle its suspected nuclear weapons programs.
North Korea's envoy to the United Nations, Han Sung Ryol, told South Korea's national news agency Yonhap that the communist state found the United States "worthless" as a dialogue partner because it was applying "double standards" to the two Koreas.
Han called South Korea's uranium enrichment experiment "a dangerous move that would accelerate a nuclear arms race in Northeast Asia," Yonhap said.
"We see South Korea's uranium enrichment experiment in the context of an arms race in Northeast Asia," Han was quoted as saying. "Because of the South Korean experiment, it has become difficult to control the acceleration of a nuclear arms race."
Han's comments were North Korea's first reaction to the South Korean admission this week that its scientists produced a small amount of enriched uranium in an experiment in 2000.
The reaction signaled that North Korea could use the South Korean experiment as leverage in any further talks on U.S.-led efforts to persuade North Korea to give up its nuclear development.
Earlier Wednesday, South Korea said it should have reported the uranium enrichment experiment to the U.N. nuclear watchdog agency.
South Korea admitted last week that its scientists produced 0.2 grams of enriched uranium during the experiment at its main government-affiliated nuclear research institute.
"We should have reported that uranium was used during this experiment," a senior official at the South Korean Foreign Ministry said on condition of anonymity. He spoke to reporters at a briefing.
South Korea has denied the experiment reflected an interest in developing nuclear weapons.
State Department spokesman Richard Boucher has criticized the secret experiment, saying it shouldn't have occurred. But he praised South Korea for working with the International Atomic Energy Agency to make sure the program has ended.
"We have confidence that the agency will pursue all these matters," Boucher said Wednesday.
Asked whether South Korea had experimented with plutonium, Boucher withheld comment, noting the United States is aware of what Seoul has reported to the IAEA about its past activities.
In the early 1970s, South Korea was developing a nuclear weapons program, but abandoned it under U.S. pressure and signed the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) in April 1975 before producing any fissile material required to make a bomb. A senior Bush administration official said Wednesday that those secret experiments involved plutonium.
The IAEA has asked "plutonium-related" questions during the course of routine investigations over the years, but the plutonium issue was not mentioned in the recent IAEA report on the uranium enrichment case, the South Korean Foreign Ministry official said.
"Regarding plutonium, there is nothing that could be interpreted as a violation of NPT like the current uranium enrichment case," the official said. He declined to comment in detail.
Han, the North Korean diplomat, complained the Bush administration was being unfair.
"The United States is applying double standards," Hans was quoted as saying. "While saying it trusts South Korea, it is trying to force North Korea to accept nuclear inspections, concocting a story about a HEU (highly enriched uranium) program we don't even have."
The latest South Korean experiment took place two years before a nuclear crisis erupted on the divided Korean Peninsula, when the United States accused North Korea of running a secret uranium enrichment program.
North Korea denied the charge but withdrew from the Nuclear Nonproliferation Treaty in early 2003. It has also restarted plutonium facilities that were mothballed under a 1994 accord with Washington.
The impoverished North said its nuclear development was for peaceful purposes. But it also says it is increasing its "nuclear deterrent" against a U.S. plan to invade, and that it will abandon its atomic development only if Washington provides nonaggression guarantees and energy and economic aid.
Washington wants North Korea to allow immediate nuclear inspections and dismantle all nuclear facilities.
Accusing the United States of breaking an earlier promise to provide economic aid in return for nuclear inspections, Han called Washington "worthless" as a dialogue partner.
The United States, Russia, Japan, China and the two Koreas have held talks on North Korea's suspected nuclear weapons development, and they agreed to hold another round of negotiations in Beijing this month. However, no date has been set.
The South Korean Foreign Ministry official said the Vienna-based IAEA will decide next week whether the South Korean experiment was a violation of international nuclear safeguard agreements.
The official insisted the experiment itself was not, but said South Korea should have reported enriched uranium had been produced.
The Ministry of Science and Technology said it learned about the experiment in June, when the government made a report to the nuclear agency after signing an additional safeguards agreement earlier in the year.
Today a South Korean delegation will depart for the IAEA's headquarters to explain the experiment and pledge transparency in its nuclear operations.
South Korea says the enriched uranium produced during the experiment was far below the amount needed for a bomb. Besides, it was enriched to only 10 percent, much lower than the 90 percent enrichment needed for bomb-making, it says.