EDIT: It has now been confirmed that the severity has been raised from level 1 to 3 on the INES scale.

Japan said on Wednesday (August 21) that it would look into dramatically raising the severity of a toxic water leak at the Fukushima nuclear plant, its most serious action since the plant was destroyed by an earthquake and tsunami in 2011.

The deepening crisis at the Fukushima plant may be upgraded from a level 1 "anomaly" to a level three "serious incident" on an international scale for radiological releases, a spokesman for Japan's Nuclear Regulation Authority (NRA) said.

If they do that will mark the first time Japan has issued a warning on the INES since three reactor meltdowns after the massive quake in March 2011.

A maximum level 7 was declared at the battered plant after explosions led to a loss of power and cooling two years ago, confirming Fukushima as the worst nuclear accident since Chernobyl a quarter of a century earlier.

Contaminated water with dangerously high levels of radiation is leaking from a storage tank at Fukushima, the plant's operator, Tokyo Electric Power Co said on Tuesday. The leak was classified as an "anomaly" earlier this week.

The leak, which has not been plugged, is so contaminated that a person standing 50 cm (1.6 feet) away would, within an hour, receive a radiation dose five times the average annual global limit for nuclear workers.

After 10 hours, a worker in that proximity to the leak would develop radiation sickness with symptoms including nausea and a drop in white blood cells.

Each one-step INES increase represents a tenfold increase in severity, according to a factsheet on the website of the International Atomic Energy Agency.

Presented by Adam Justice