Toxic radioactive isotope found in Fukushima groundwater

High levels of a toxic radioactive isotope have been found in groundwater at Japan's Fukushima nuclear plant, its operator says.

Tokyo Electric Power Company (Tepco) said tests showed Strontium-90 was present at 30 times the legal rate.

The radioactive isotope tritium has also been detected at elevated levels.

The plant, crippled by the 2011 earthquake and tsunami, has recently seen a series of water leaks and power failures.

Rupert Wingfield-Hayes reports from Japan.