Investors are counting on reconstruction spending to help the world's third-largest economy pull out from a slump caused by the disasters and say that without substantial spending, it may not be able to resume moderate growth.

To raise the money, the government is considering issuing special bonds, scaling back other spending plans and selling national assets, said the source who declines to be identified.

The government has yet to finalize the maturity periods for the planned reconstruction bonds but the Ministry of Finance is planning 5 year bonds, the source said.

Tokyo will consider seeking tax hikes to repay the bonds, the source said.

Government officials have said that further reconstruction-related spending could be more than 10 trillion yen.

The 13 trillion yen spending would translate into projects worth around 23-25 trillion yen, the source said, adding that the projects would be implemented over 10 years with 80 percent of them in the first five years, the source said.

The reconstruction plans, however, do not include how to deal with the crisis at the crippled Fukushima nuclear plant that has leaked radiation since the disaster in the world's worst nuclear accident since Chernobyl.

With public debt already twice the size of the US$5 trillion economy, the government has so far funded the previous two extra budgets without new borrowing while tapping fiscal reserves and reallocating spending.