North Korea (search) on Wednesday warned of a "nuclear arms race" in Northeast Asia following the recent revelation that South Korean scientists enriched a tiny amount of uranium (search) four years ago, a news report said.

North Korea's envoy to the United Nations (search), 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's comments were North Korea's first public reaction to the South Korean admission last 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 international efforts to persuade North Korea to give up its suspected nuclear weapons development.

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."

Earlier Wednesday, South Korea said it should have reported the uranium enrichment experiment in 2000 to the U.N. nuclear watchdog.

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.

The Foreign Ministry official said the Vienna-based International Atomic Energy Agency (search) will decide next week whether the South Korean experiment was a violation of international nuclear safeguard agreements.

The official insisted that the experiment itself was not a violation, but said South Korea should have reported the production of enriched uranium.

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.

On Thursday, a South Korean delegation was to 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. In addition, it was enriched to only 10 percent, much lower than the 90 percent enrichment needed for bomb-making, it says.

The United States, Russia, Japan, China and the two Koreas have held talks on North Korea's suspected nuclear weapons development and agreed to hold another round of negotiations in Beijing this month. However, no date has been set.