A Japanese utility has said its crippled Fukushima nuclear plant is likely to have leaked contaminated water into sea, acknowledging for the first time a problem long suspected by experts.

Experts have suspected a continuous leak since the Fukushima Dai-ichi plant was ravaged by the March 2011 earthquake and tsunami.

Operator Tokyo Electric Power Co. had previously denied contaminated water reached the sea, despite spikes in radiation levels in underground and sea water samples taken at the plant. Japan's nuclear watchdog said two weeks ago a leak was highly suspected, ordering TEPCO to examine the problem.

TEPCO said Monday the leak has stayed near the plant inside the bay.

TEPCO is struggling to manage leaks of water used to cool the wrecked reactors, a risk hampering the plant's decommissioning efforts.