The U.S. Federal Reserve's emergency $85 billion rescue of the U.S. insurer American International Group eased concerns Wednesday that its Japanese unit will survive, at least for the time being.

"It means that the U.S. government and financial authorities are tackling the problem to avoid a negative chain reaction triggered by the collapse of Lehman Brothers," Chief Cabinet Secretary Nobutaka Machimura said at a news conference.

If AIG were to collapse, the Financial Services Agency would have to quickly issue an order to keep all assets of AIG Japan in the country to protect the contracts of policyholders, a top agency official said on condition of anonymity.