Story highlights TEPCO looking for outside help to safely decommission the crippled plant

Nuclear Regulation Authority says new toxic leak expected to be classified a level 3 incident

The International Atomic Energy Agency says it "views this matter seriously"

The warning is the highest since the 2011 earthquake and tsunami triggered a meltdown

The operator of the crippled Fukushima nuclear plant has said they need help from outside Japan to stabilize and safely decommission damaged reactors at the facility.

This follows the news that regulators are poised to declare a fresh toxic water leak at Fukushima a level 3 "serious incident," the gravest warning since the massive 2011 earthquake and tsunami that sent three reactors into meltdown.

Zengo Aizawa, vice president of the Tokyo Electric Power Company (TEPCO), told reporters at a press conference late Wednesday that there are "many other countries outside of Japan that have experienced decommissioning reactors, so we hope we can consult them more and utilize their experience.

"In that sense, we need support, not only from the Japanese government but from the international community to do this job."

Earlier Wednesday, Japan's Nuclear Regulation Authority (NRA) said the new leak was expected to be classified as a level 3 incident on the International Nuclear and Radiological Event Scale , though this will be done once they have received an opinion from the Vienna-based International Atomic Energy Agency (IAEA). The NRA said they have received a first response from the IAEA asking for more details about the leaking tank, especially the structure and its initial role.

"The current situation is at the point where more surveillance won't be enough to keep the accidents from happening," Shunichi Tanaka, chairman of the NRA, said at a news conference Wednesday.

"Our job is now to lower the risk of these accidents from becoming fatal."

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The leak previously had a level 1 "anomaly rating" on the scale, which ranges from zero, for no safety threat, to seven, for a major accident like the meltdowns at the plant after the earthquake and tsunami.

TEPCO, which is in charge of the plant, has struggled to manage the vast quantities of contaminated water at the plant since the tsunami, which swamped the facility.

Water pumped out of the stricken reactor buildings is being stored in large water towers at the site.

In response to the latest leakage of 300 tons of toxic water, a TEPCO spokesman said Wednesday the company has finished removing radioactive water from a leaky tank and transferred it to another tank at the plant.

The leaky container is designed to hold as much as 1,000 tons of water, TEPCO said.

The International Atomic Energy Agency said it was aware of reports that the Nuclear Regulation Authority plans to rate the leak as a level 3 incident.

"The IAEA views this matter seriously and remains ready to provide assistance on request," the agency said.

Scientists have pointed to high radiation levels in the waters off the plant for more than a year as evidence of problems with the company's efforts to contain the water.

In July, TEPCO admitted that radioactive groundwater was leaking into the Pacific Ocean from the plant, even though an underground barrier was built to seal in the water, underscoring a growing sense of crisis at the site.

The authority said in a statement on its website that the plant "remains in an unstable condition, with various risks to be addressed, and in particular managing the issue of contaminated water as a high priority."

Michael Friedlander, a nuclear engineer and former U.S. power plant operator, said the level 3 classification was warranted for the type of situation faced by TEPCO, but he said the risk to the public outside the plant was very low.

"This is extremely radioactive water, and it would pose a very significant risk to the workers who are going to be in a position to clean it up," he told CNN.

"It's a very difficult situation because we don't know exactly know where the leak is coming from."

But TEPCO spokeswoman Mayumi Yoshida disputed Friedlander's assessment of the risk posed by the contaminated water. She said workers removing the water from the tank have sufficient protective clothing to prevent exposure.

Amid growing concerns this month about contaminated groundwater leaching into the ocean from the plant, Prime Minister Shinzo Abe ordered his government to find "multiple, speedy and sure" ways to stop the water's spread.

"We have to deal with this at a national level," he said.

But experts say that any potential solutions are likely to be difficult, technologically and politically.