South Korea has confirmed that it conducted plutonium-based nuclear research in the early 1980s.
South Korea's Science and Technology Ministry says government scientists extracted a small amount of plutonium during an experiment in 1982 at a state-run research reactor in Seoul.
Last week, Seoul acknowledged it had conducted nuclear fuel tests in 2000, but said they were an isolated experiment and not part of any nuclear weapons development program.
North Korea issued its first public reaction to the nuclear fuel issue Wednesday, warning of a potential nuclear arms race in southeast Asia.
South Korean officials acknowledged they should have reported the nuclear fuel experiment when it occurred in 2000.
Information for this report is provided by Reuters.