AIG in 'Crisis,' Ex-Chief Says

Meanwhile, there's plenty of bad blood between Greenberg and the global financial giant that he built. AIG recently sued him and six other former executives, alleging they misappropriated $20 billion worth of the company's shares.

The suit, filed in a New York state court, says Greenberg, Howard Smith, Edward Matthews, Ernest Stempel, L. Michael Murphy, John Roberts and Houghton Freeman, while members of Starr's board in 2005, "misappropriated" AIG stock held by the firm "for their own benefit," according to media reports. Starr is an entity created to protect AIG from a hostile takeover.

Last year, Greenberg and the other Starr executives launched a criticism of the direction and management of AIG in another SEC filing. In January, Mr. Greenberg said he wouldn't launch a proxy battle or serve again as an AIG officer or director, and said that he and the affiliated shareholders "do not currently intend to initiate a tender offer."

Greenberg's letter comes as pressure mounts for AIG CEO Martin Sullivan in the wake of the company's problems amid the credit crunch. The crisis already has claimed CEOs at Merrill Lynch(MER Quote), Citigroup(C Quote), Bear Stearns(BSC Quote) and MBIA(MBI Quote) since last summer.

Meanwhile, The Wall Street Journal reported Monday that International Lease Finance Corp., an airplane-leasing giant run by one of AIG's largest shareholders, is considering splitting away from the insurance conglomerate to avoid being caught up further in its financial woes. ILFC is one of AIG's most profitable businesses.

Shares of AIG closed down $1.91, or 4.7%, to $38.37.