Radioactive contamination from the stricken nuclear power facility Fukushima has worsened, the operators Tepco warned Sunday, with probes of groundwater turning up traces of strontium that were 240 times above the allowable maximum limit, dpa reported.
Nuclear regulatory authorities reported finding the dangerously radioactive element near the damaged reactors 1 and 2.
The Kyodo news agency said it was the first discovery of strontium in the groundwater and was possibly caused by leakage resulting from pipelines being stopped up.
Meanwhile Tepco said that due to technical problems it could not yet start testing a new facility to decontaminate the tainted water.
Tepco had planned to start a week of testing on Friday, but due to the problems the start-up of the new facility - originally targeted for mid-June - would be delayed.
The decontamination facility poses a key element in Tepco's hopes of recycling the thousands of tons of highly-contaminated water used for cooling the reactors.