Tokyo Electric Power Company (TEPCO) on Friday asked Japan's government for a reported $13 billion to help pay compensation for the Fukushima nuclear disaster.

"Today, we, Tokyo Electric Power Company, applied to the Nuclear Damage Compensation Facilitation Corporation for financial support," TEPCO said in a statement.

The company did not reveal the amount of cash it asked for and said the figure would remain secret until it was approved by the government.

However, media reports put the figure at up to one trillion yen ($13 billion).

The utility is looking to receive the first tranche from a government-backed aid body so it can avoid having a negative net worth on its April-September balance sheet, local media reported.

The Yomiuri daily reported that TEPCO needed a trillion yen "for the time being", indicating that the embattled company may go cap in hand to the government for more help later.

The utility also submitted an emergency business plan to Prime Minister Yoshihiko Noda and trade minister Yukio Edano, who supervises the energy industry, it said.

The plan outlines cost cuts, asset sales and other restructuring steps required to help it meet compensation costs -- estimated by a government panel at 4.5 trillion yen by 2013 -- and secure further state help.

Edano will look at the details of the request and the business plan before deciding on whether to approve it in early November, news reports said.

Separately, a government panel on Friday said decommissioning the crippled nuclear plant was likely to take 30 years or more, local media reported.

"We set a goal to start taking out the (core) debris within a 10-year period," the panel under the Japan Atomic Energy Commission said in a draft, according to Kyodo News.

"It is estimated that it would take 30 years or more to finish decommissioning."

TEPCO's woes began when the magnitude-9.0 quake and massive tsunami of March 11 knocked out cooling systems at the Fukushima plant, sparking meltdowns, a series of explosions and the release of huge amounts of radiation into the environment.

Tens of thousands of people remain evacuated from homes and businesses in a 20 kilometre (12 mile) no-go zone around the plant and in pockets beyond. Fully decontaminating those areas is expected to take decades.

The task of restoring towns and villages even in lightly polluted zones is complicated, with high costs and logistical difficulties over where to store soil contaminated with radioactive material.

Radioactive hotspots have also been found hundreds of kilometres away from the Fukushima Daiichi plant in parts of Tokyo and Yokohama, with rainfall and wind patterns blamed for the uneven dispersal.

The disaster has soured the mood among the Japanese public over nuclear power, with many worried about the health effects of the technology, which until March had provided a third of resource-poor Japan's electricity.

A government panel earlier this month said that TEPCO would have to cut 7,400 jobs and slash costs by $33 billion over the next 10 years to help pay damages for the nuclear accident.