Secret South Korean nuclear experiments revealed earlier this year produced minute amounts of weapons-grade uranium and plutonium, but there was no evidence they were applied to an arms program, the U.N. atomic watchdog said Thursday.

The report, drawn up by the International Atomic Energy Agency (search) and made available to The Associated Press, followed up on revelations that South Korea dabbled in uranium enrichment (search) and plutonium reprocessing (search).

Officials subsequently acknowledged the experiments but insisted they were small-scale and conducted by scientists who never informed the government.

Beyond establishing that those experiments produced minute amounts and had been restricted to the laboratory, the report also revealed a separate attempt at uranium enrichment.

But the report said this attempt — to enrich uranium chemically — resulted in extremely low enrichment, far below the 90 percent minimum normally used to make arms.

The experiments were conducted in January-February 2000 at the government-affiliated Korea Atomic Energy Research Institute (search).

The institute's president, Chang In-soon, said there were three or four tests, but the amount involved was "so small it's almost invisible."

South Korea also admitted conducting a plutonium-based nuclear experiment in 1982.

South Korea scrambled to deny it had ambitions for a nuclear program after the admission that scientists conducted the unauthorized experiments. The revelation threatened to complicate an international standoff over communist North Korea's nuclear weapons development.

Pyongyang has cited South Korea's nuclear activities as a major reason for its reluctance to rejoin six-nation talks aimed at ending its atomic weapons program.