American International Group Inc., under regulatory scrutiny, is about to correct suspected accounting mistakes that may cost $3 billion from as many as 30 insurance transactions, according to the people familiar with the inquiry.

The potentially problematic accounting now being scrutinized has turned out to be broader than it was stated just a week ago, said people familiar with the situation.

The nation’s largest insurer has yet to evaluate additional 60 transactions that internal AIG investigators have named as possibly problematic, said one person familiar with the examination. Some senior AIG executives were informed about many of these transactions, this person said, which could subject them to regulatory investigation.

Last week, questions over AIG’s accounting of an insurance transaction with a Berkshire Hathaway Inc. resulted in Maurice R. "Hank" Greenberg’s retirement as AIG’s chief executive. Investigators proceed investigating whether AIG deceived investors by manipulating its books. This week, AIG, which has promised to collaborate with investigators, dismissed its chief financial officer and a senior reinsurance executive after they took decision not to answer some questions on the grounds that their answers might be self-incriminating, according to the Wall Street Journal.

An AIG spokesman, Chris Winans declined to comment.

Though it remains unclear how AIG might answer for its mistakes, since even a multibillion-dollar charge against earnings likely wouldn’t hurt its long-term financial stability. The company reported net income of $11.04 billion in 2004 on revenue of $98.61 billion.

The potential errors cover five years, and comprise the possible booking of revenue and income prior than they should have been registered up to the crossing of liabilities off the company’s books, even as AIG bears responsibility for those obligations, said one person familiar with the inquiry.