NEW YORK (Bloomberg) — American International Group Inc., the world's biggest insurer by assets, paid more than $2.2 billion to a firm controlled by former chief executive officer Maurice (Hank) Greenberg, according to investors seeking to recoup almost half of that amount.

CV Starr & Co. collected about $1.8 billion in commissions and fees from AIG during a six-year period starting in 2000, lawyers for a Louisiana pension fund said in a July 16 filing in Delaware Chancery Court. Greenberg, who stepped down as AIG's CEO in March 2005, is Starr's chairman and chief executive and held those posts while at AIG.

AIG shareholders also claim the New York-based company paid $450 million in subsidies to Starr in the form of free services provided by AIG employees, lawyers for the defendants said in Chancery Court filings. Starr, Greenberg and other former AIG executives should repay at least $1 billion, the investors said.

The defendants showed a "blatant disregard of AIG's economic interests" by taking the payments, according to a pre- trial brief. The claims are set for trial September 15 before Judge Leo Strine in Wilmington, Delaware.

The Teachers' Retirement System of Louisiana sued Greenberg, 83, in 2002 for allegedly siphoning millions from AIG through the payments to Starr. The fund contends commissions and fees paid to Starr were a sham to benefit Greenberg and other AIG executives who own the closely held insurance agency.

"CV Starr is confident that once the court hears all the evidence, it will conclude, just as a special independent committee of the board of AIG concluded, that all transactions between AIG and C.V. Starr were proper and entirely fair to AIG and its shareholders," Glen Rochkind, a spokesman for Starr and Greenberg, said in an e-mailed statement.

Chris Winans, an AIG spokesman, declined to comment on the filings.

Greenberg, who has denied any wrongdoing, stepped down amid accounting probes by state and federal officials before AIG restated profit by $3.9 billion. The company also agreed to pay more than $1.6 billion to settle allegations by former New York Attorney General Eliot Spitzer and the US Securities and Exchange Commission that it misled shareholders and cheated workers' compensation programmes.

The probes found that Starr was enmeshed with AIG's operations, the Louisiana fund's lawyers say. Starr's business units split offices with counterparts at AIG, and the companies shared employees and executives, according to the investor suit. AIG officials could have handled the tasks for which it paid Starr, and the commissions were simply a means for Greenberg and other Starr directors to line their pockets, investors contend.