A small amount of chlorine gas leaked from a SK hynix Inc. semiconductor plant in central South Korea Friday but no one was injured, fire officials and the company said.

The world's No. 2 memory chip maker, however, did not report the leak to authorities immediately, fire officials said.

According to fire officials and SK hynix, 0.17 grams chlorine gas leaked from one of the SK hynix factories in Cheongju, about 137 kilometers south of Seoul, around 10:10 a.m.

Fire officials said they became aware of the incident four hours later, only after receiving an anonymous tip-off.

Company officials said it was a "minor incident" and that the facility was normalized within an hour, adding that the employees have returned to work.

SK hynix officials said at the time of the leakage, four employees were working on pipes, and they were all wearing protective gear. Workers shut down the valve within about 10 seconds after they detected strange odor, the officials said.

According to company officials, the concentration of chlorine gas in the air fell from 1.8 parts per million (ppm) to the normal level of 1 ppm within seconds.

"You'd have to be exposed to more than 1 ppm of chlorine gas for over eight hours to have any damage to the body," one company official said.

(Yonhap News)