Japan has decided to reduce its stockpile of plutonium under its principle of possessing only an amount necessary for peaceful use, the country's nuclear panel said Tuesday, but without giving a numerical target.

The Japan Atomic Energy Commission also said in the revised policy guideline that the production of plutonium at the planned Rokkasho reprocessing plant should be limited to an amount required as fuel for nuclear reactors in the country.

(The Rokkasho reprocessing plant)

The revision to the 2003 policy on the use of plutonium came amid concerns about Japan's increasing stockpile and uncertainty about its policy of recycling spent nuclear fuel following the 2011 Fukushima disaster.

In its updated policy, the panel said Japan has taken into account "recent circumstances surrounding the use of nuclear energy not only in Japan but also in the world," while pledging to cooperate with the international community to work toward nuclear non-proliferation.

The commission, however, did not specify a cap on the amount of plutonium allowed to be possessed and a deadline for curbing the stockpile.

Some countries, including the United States which has allowed Japan to extract plutonium and enrich uranium for decades, are seen as concerned about its increasing stockpile of plutonium.

On July 17, Japan and the United States extended a bilateral nuclear agreement beyond its initial 30-year period that has served as the basis for Tokyo's push for a nuclear fuel recycle policy.

Japan had a total of 47.3 tons of plutonium at the end of 2017, up from 46.9 tons the year before, which is enough to produce about 6,000 nuclear warheads.

Most of the total, or about 36.7 tons, was stored overseas -- 21.2 tons in Britain and 15.5 tons in France. About 10.5 tons are kept in Japan, according to the government.

The panel said Japan will aim to keep the stockpile from rising further from the current levels by taking a series of measures, including steadily curbing its overseas stockpile.

Despite the latest pledge, it remains to be seen whether Japan can actually curb its possession of plutonium once the Rokkasho fuel reprocessing plant starts operating, nuclear experts say.

The plant in Aomori Prefecture, northeastern Japan, is now expected to be completed in the first half of fiscal 2021 following repeated delays. When fully operational, it is designed to extract about 8 tons of plutonium by reprocessing up to 800 tons of spent fuel per year.

Resource-poor Japan has been pushing for a fuel cycle policy. Spent fuel from nuclear reactors is reprocessed to extract uranium and plutonium, which is then recycled into fuel called mixed oxide, or MOX, for use in fast-breeder reactors or conventional nuclear reactors.

But most of the country's nuclear reactors remain offline amid safety concerns and public opposition and the prospects are dim for active use of such MOX fuel. Currently, only four nuclear reactors can burn it.

In a setback for nuclear fuel recycling, the government decided in 2016 to scrap the trouble-plagued Monju prototype fast-breeder reactor.