* Postal minister says share sale to come in stages
* Nikkei says total proceeds could reach $87 bln
* Money would be used to pay for disaster reconstruction
* Bankers skeptical that plan will go ahead
TOKYO, Oct 26 (Reuters) - Japan unveiled plans on Friday to list shares of state-owned Japan Post Holdings Co, which runs the country's biggest savings institution, within three years to raise money to rebuild areas devastated by last year's quake, tsunami and nuclear crisis.
The government said it would sell down in stages and that it did not yet know how much money it would raise, though the Nikkei business daily said proceeds could reach 7 trillion yen ($87 billion) from gradually selling a two-thirds stake.
Some skeptical bankers, however, doubted the plan would even go ahead, saying it would have to overcome opposition from the financial services industry and navigate a political minefield.
``It is important for the government to sell off shares in Japan Post because these funds will be used for our reconstruction effort,'' Finance Minister Koriki Jojima told a news conference.
``I hope we can secure as high a price for the shares as possible.''
Japan Post is a financial goliath which plays an influential role in the world's third-largest economy: its banking unit holds savings deposits totalling roughly 176 trillion, or about one-fifth of Japan's total cash and deposits.
Its insurance arm is also a huge holder of Japanese government bonds, indirectly helping to keep interest rates low on Japan's mountain of sovereign debt, while its postal service is a political asset that employs more than 200,000 people.
``This has been on and off again for years,'' said one Tokyo-based banker, referring to previous political debates over privatising Japan Post.
His comment reflected general concerns over obstacles to successfully selling the sensitive state asset.
Bankers said Japan's mega-banks and insurers - as well as U.S. insurers - would likely oppose the move, fearing the government's continued minority ownership of Japan Post would give the firm's financial arms an unfair competitive advantage.
To ensure a successful share sale, Japan Post might also have to overhaul its loss-making postal business, a politically tricky task given its big workforce and the traditional clout of postmasters as mobilisers of votes in rural areas.
Even then, investors may not be all that enthused.
Japan Post made net profit of 469 billion yen in the year to March 2012, but the banking arm provided the bulk of that profit, while the mail service made a loss of 4.5 billion yen in 2011/12, hit by a continued decline in mail traffic.
Tokyo plans total spending of 19 trillion yen over the next five years to rebuild its northeast from the March 2011 disasters. The government aims to raise 9.2 trillion yen of that through higher taxes while targetting another 7 trillion or more mainly through selling government shares in Japan Tobacco Inc , Japan Post and energy-related firms.
The plan to sell Japan Post come at a politically uncertain time, with Japanese voters likely to change the government at elections due by August 2013 but expected to be held sooner.
A selldown of Japan Post has been on the political drawing board for years, but has never made much headway.
Legislation enacted in 2005 under then-Prime Minister Junichiro Koizumi, who made postal privatisation his signature reform, had required the government to sell shares in the Japan Post's financial units by the end of September 2017, but revisions enacted in April of this year dropped that deadline.
Post minister Mikio Shimoji said on Friday that shares in the financial units might also be offered separately for sale, though it was unclear why shares might be offered in both the units and the parent company.
The shares in the units would only be offered once the government's holding-company stake fell below half, Shimoji dded.
In one of its biggest privatisations, the government raised about 15 trillion yen from selling shares in Nippon Telegraph and Telephone Corp in stages beginning in 1986.