Japan's Environment Ministry has presented a proposal for the final disposal of soil exposed to radioactive fallout from the Fukushima Daiichi nuclear plant accident.

The ministry held a panel of experts on Friday and presented four options for disposing of soil and waste collected in the decontamination work. Fourteen million cubic meters of the material are kept at an interim storage facility.

A law mandates that the soil must be finally disposed of outside the prefecture by 2045.

The government plans to re-use some of the soil for public works projects nationwide. It plans to dispose of the rest.

The ministry says there are four options for disposing of the soil. The more extensively the soil is treated, the less of it there will be left for final disposal.

With the option of giving the soil extensive treatment, the volume of soil for final disposal will be below 100,000 cubic meters. But radioactive concentrations will be tens of millions of becquerels per kilogram.

The soil needs to be contained in concrete and buried underground. About 3 hectares of land will be needed.

Another option is to give the soil the simplest treatment. Up to 3.1 million cubic meters of soil will need to be disposed of, and the levels of radioactive substances will be tens of thousands of becquerels.

Most of the soil will be covered by other soil, and up to 50 hectares of land will be needed for the site.

Ministry officials think the decision of other prefectures on whether to host a final disposal site will depend on the volume of soil and the concentrations of radioactive materials.

The officials hope to start looking for candidate sites from the next fiscal year that starts April.