Tokyo Electric Power Company says water may be leaking from breaches in the No.1 reactor at the Fukushima Daiichi nuclear plant, causing a sharp drop in the water level inside the reactor.

Tokyo Electric sent workers inside the building to adjust the water gauge of the reactor.

The utility had suspected the gauge wasn't working properly because the water level hasn't been rising despite pumping in 150 tons of water daily to cool the reactor.

On Thursday morning, it was found that the water level was more than one meter below the bottom of the fuel rods, suggesting a large volume of water is leaking into the containment vessel.