The release of treated wastewater into the ocean from the wrecked Fukushima nuclear plant was suspended on Wednesday as a partial power outage affected the site, operator Tokyo Electric Power Holdings (Tepco) said.

Tepco said in a statement that the system to cool reactors remained operational and "no meaningful change" had been detected at plant facilities that monitor radioactivity.

In 2011, the Fukushima No. 1 plant on Japan's northeastern coast went into meltdown after a huge earthquake and tsunami that killed 18,000 people. It was one of the worst nuclear disasters in history.