Radioactive water is leaking from the broken Fukishima nuclear power plant into the Pacific Ocean, with rumours now confirmed by the plant’s operator.

The Tokyo Electric Power Company (TEPCO) has admitted for the first time that radioactive groundwater has leaked, after months spent trying to prevent it from seeping in and becoming contaminated.

A TEPCO spokesperson says they believe the impact on the ocean will be minimal, though it provided no explanation for samples taken at the Fukushima plant that showed levels of radioactive caesium had increased by more than 100 times in just a few days.

The leak has also been observed by users of the Geiger monitoring system Safecast, which has gathered more than ten million data points on radiation since the 2011 disasters. Observers have noted a reduction in the radiation levels that is faster than the material’s half-life, suggesting radioactive materials are moving and spreading away from the site.

An earthquake and tsunami in March 2011 knocked out cooling systems at the Fukushima plant, triggering fuel meltdowns and causing radiation leakage, food contamination and mass evacuations. The head of Japan's Nuclear Regulation Authority now believes contamination of the sea has been continuing since the explosions at Fukushima following the tsunami.

A regularly updated chart of user-collected global Geiger information is available here.