TOKYO — Three hundred tons of highly contaminated water have leaked from a storage tank at the ravaged Fukushima Daiichi Nuclear Power Plant on Japan’s Pacific Coast, its operator said on Tuesday, raising further concerns over the site’s safety and prompting regulators to declare a radiological release incident for the first time since disaster struck there in 2011.

Workers raced to place sandbags around the leak at the site to stem the spread of the water, a task made more urgent by a forecast of heavy rain for the Fukushima region later in the day. A spokesman at Tokyo Electric Power, the plant’s operator, acknowledged that much of the contaminated water had seeped into the soil and could eventually reach the ocean, adding to the tons of radioactive fluids that have already leaked into the sea from the troubled plant.

The leaked water contains levels of radioactive cesium and strontium many hundreds of times higher than legal safety limits, Tokyo Electric said. Exposure to either element is known to increase the risk of cancer.

The company said it had not determined the source of the leak.

Click here for the full story.