Visiting fellow Dr Peter McCawley at The Australian National University on Monday called on Japan to announce an overall strategy if it is to successfully respond to the nation's unfolding natural disaster.

McCawley, a visiting fellow in the ANU Crawford School of Economics and Government, warned that unless an overall strategy is announced soon, a coordinated and effective response to the disaster will become less likely.

"Of course all eyes in Japan, as well as the international community, are currently focused on the immediate issues," said Dr McCawley. "There is much concern about the dangers arising from the damage to the nuclear electricity plants in Fukushima, and the humanitarian needs of the survivors are very urgent.

"But unless an overall strategy is announced quite soon, problems of coordination can be expected to become more difficult very soon."

Dr McCawley, who has been researching the recovery process after the 2004 Asian tsunami, added that past experiences elsewhere showed that responses to mega-disasters need to be delivered in stages.

"It is often a useful strategy to have five main stages," said Dr McCawley. "These include the immediate response, the early relief stage, later rehabilitation, large-scale reconstruction and the return-to-normal stage.

"The stages are important for policy making because the needs of the affected people vary according to the stages, and because the appropriate public policy responses are rather different in each stage.

"There is already talk that spending programs of well over $100 billion will be needed in Japan to assist recovery from the disaster. This sounds right. In the USA post-Hurricane Katrina expenditures were over $100 billion.

"Post-tsunami recovery in Japan will therefore be a huge project. It isn't easy to spend $100 billion well. Careful but reasonably rapid programs need to be drawn up across hundreds of agencies. This is why the early preparation of a roadmap for recovery is needed as soon as possible," he said.