Japanese officials investigating a small radiation hotspot in Tokyo say it was caused by old bottles stored in the basement of an empty house, not the country's leaking nuclear power plant.
Officials had detected levels of radioactivity higher than those in the evacuation zone around the damaged Fukushima Dai-ichi nuclear plant after concerned parents checking the neighbourhood for radiation sought further tests.
The plant is about 150 miles north-east of Tokyo.
Mayor Nobuto Hosaka said the hotspot was most likely caused by a radioactive material in several old bottles in the house. Radioactivity from the bottles exceeded the measurable limit on a low-dose radiation counter.
Science and education ministry inspectors believe the bottles contain radium, a radioactive material used in the past as self-luminous paint for watches.
The inspectors decided that the radiation was not related to the Fukushima disaster because no caesium was detected in the bottles.
Caesium is one of the main isotopes that leaked from the tsunami-damaged nuclear plant.
Police are investigating whether the bottles violated laws regulating possession of radioactive materials.
Officials say the radiation level did not present a health risk.