Inspectors from the United Nations nuclear watchdog are in South Korea to resume their probe into the country's secret nuclear experiments.
This is the third time the International Atomic Energy Agency has sent a team to South Korea. The inspectors are collecting material for a report to the agency's board later this month.
The board then will decide whether to refer the case to the U.N. Security Council.
South Korea has admitted that it conducted a plutonium-based experiment in 1982, as well as a uranium-enrichment test in 2000. Seoul says the experiments were purely for academic, scientific purposes.
North Korea has said Seoul's nuclear activities are one of the reasons it will not return to six-party talks on ending its nuclear ambitions.
Some information for this report provided by AFP and AP.