The panel sharply criticized AIG's former top executives, summoned to the hearing, who cast blame on one another for the firm's financial woes.

"You have cost my constituents and the taxpayers of this country $85 billion," said Rep. Carolyn Maloney (D., N.Y.). "You were just gambling billions, possibly trillions of dollars."

AIG, crippled by huge losses linked to mortgage defaults, was forced last month to accept an $85 billion government loan that gives the United States an 80 percent stake in the company.

House Oversight Committee Chairman Henry Waxman (D., Calif.) introduced documents showing AIG executives hid the full extent of the firm's risky financial products from auditors, both outside and inside the firm, as losses mounted.

For instance, federal regulators at the Office of Thrift Supervision warned in March that "corporate oversight of AIG Financial Products . . . lack critical elements of independence."

At the same time, outside auditor PricewaterhouseCoopers confidentially warned the company that the "root cause" of its mounting problems was denying internal overseers in charge of limiting AIG's exposure access to what was going on in its highly leveraged financial-products branch.

Waxman also released testimony from former AIG auditor Joseph St. Denis, who resigned after being blocked from giving his input on how the firm estimated its liabilities.

Three former AIG executives were summoned to appear before the hearing. One of them, Maurice "Hank" Greenberg - who ran AIG for 38 years until 2005 - canceled his appearance, citing illness, but submitted prepared testimony. In it, he blamed the company's financial woes on his successors, former chief executive officers Martin Sullivan and Robert Willumstad.

Sullivan and Willumstad, in turn, cast much of the blame on accounting rules that forced AIG to take tens of billions of dollars in losses stemming from exposure to toxic mortgage-related securities.

Lawmakers upbraided Sullivan, who ran the firm from 2005 until June of this year, for urging AIG's board of directors to waive pay guidelines to win a $5 million bonus for 2007 - even as the firm lost $5 billion in the fourth quarter last year. Sullivan countered that he was mainly concerned with helping other senior executives.

Sullivan also came under fire for reassuring shareholders in December of the firm's health just days after auditor PricewaterhouseCoopers warned him AIG was displaying "material weakness" in its exposure to potential losses from mortgage-related securities.