Yoshihiko Noda will call an extraordinary cabinet meeting where he will order the stimulus, the daily newspaper Yomiuri Shimbun reported.

The cash is likely to be used for measures to boost energy and environment-related industries as well as agriculture, forestry and fisheries, and for rebuilding regions hit by last year's massive tsunami disaster, it said.

As the stimulus will be financed with discretionary reserves from the current fiscal year budget, it will not need parliamentary approval, the paper said.

The Asahi Shimbun reported a similar story on its website, noting the usual route of stimulus through legislation would be difficult in a deeply divided parliament where Noda's majority is small.

The reports come months after Noda was bounced into promising an early general election in exchange for opposition support on a bill to double Japan's sales tax.

The legislation was an attempt to partially plug the country's vast debt hole, and was supported by international bodies, the press and most domestic commentators, but was unpopular among the public.

Observers say his factionally-divided Democratic Party of Japan is likely to suffer at the hands of voters disappointed by a lacklustre three years in office.