Traces of radioactive substances have been found in some fish in Korean waters.

The Korean Institute of Nuclear Safety said on Monday that it tested 23 samples of fish, shellfish and seaweed and found up to 0.253 becquerels of radioactive cesium-137 per one kilogram in a number of species of fish, including mackerel.

The institute stated that the amount is at a standard level and that the detection cannot be seen as an effect stemming from the Fukushima nuclear power plant radiation leaks. It added that there was no radioactive iodine nor radioactive cesium-134 found in the fish.

The institute also said that no radiation was found in 23 samples of seawater.