Reuters has reported a new 300 metric tons leak of contaminated water with dangerously high levels of radiation from a storage tank at Japan’s crippled Fukushima nuclear plant, the most serious setback to the cleanup of the worst nuclear accident since Chernobyl.

A Tokyo Electric (aka Tepco) official said workers failed to detect the leak of water at an early stage.

Although the Japanese government said it will step up its involvement in the cleanup, it is not clear what new measures are being taken. Given that massive amounts of radioactive fluids are accumulating at the plant it is highly likely that further leaks and contamination will ensue. Already12 workers decommissioning the plant were found to have been contaminated by radiation and fish have been also found to be contaminated.