American International Group Inc
What happens to AIG has the potential to trigger a cascading set of further failures which cannot be stopped except by extraordinary means, the agency quoted the presentation.
AIG warned its failure could cripple money-market funds, force European banks to raise capital, cause competing life insurers to fail and wipe out the taxpayers' stake in the firm, the agency said.
The presentation said without more U.S. help, investment losses would mean AIG will not be able to repay its obligations and that cash previously provided by the U.S., which controls a 79.9 percent stake in the insurer, could be lost, it added.
AIG could not be immediately reached by Reuters for comment.
The Federal Reserve first rescued AIG in September with an $85 billion credit line after losses from toxic investments and collateral demands from banks left AIG facing bankruptcy.
Late last year, the rescue packaged was increased to $150 billion. The bailout was overhauled again last week to offer the insurer an additional $30 billion in equity.
(Reporting by Ratul Ray Chaudhuri in Bangalore; Editing by Jon Loades-Carter)