Contaminated water may have leaked from the disaster-struck Fukushima No. 1 nuclear power plant since April, the owner said Thursday.

Tokyo Electric Power Company Holdings Inc. said it is still unknown, due to a problem with monitoring equipment, whether radiation-contaminated water actually leaked from the damaged reactor buildings.

In one of the world's worst nuclear disasters, reactors 1, 2 and 3 experienced fuel meltdowns while reactors1, 3 and 4 units were also severely damaged by hydrogen explosions following a massive earthquake and tsunami in March 2011.

To prevent leakage of tainted water, Tepco has installed water-level indicators and kept groundwater levels in wells higher than the contaminated water levels inside the buildings.

The water level in the wells is usually kept a meter higher than the level of tainted water inside the buildings, according to Tepco.

Source: ANNnewsCH