A warning of a radioactive leak was issued at a state-run nuclear power research institute in the central city of Daejeon on Sunday, but no radiation leaked outside, institute officials said.

The Korea Atomic Energy Research Institute, located 164 kilometers south of Seoul, said it sounded the warning at 2:32 p.m. as the radiation level of its research reactor, the 30 megawatt HANARO unit, surpassed the permitted emission limit.

The issuance of a "white" warning, the lowest on a three-tiered warning system, prompted three employees at the institute to take shelter, but there was no report of any casualties, the KAERI said. (Yonhap News)