NEW YORK (Bloomberg) ? Aon Corp. and Willis Group Holdings Ltd., two of the insurance brokerages subpoenaed last month by New York Attorney General Eliot Spitzer over fees they charge insurers, said the New York Department of Insurance also began an inquiry into the payments.

?Both of these inquiries are at the preliminary stages,? Aon said in a filing with the Securities and Exchange Commission. Willis has also received a request for information, spokesman Dan Prince said.

Aon said on Tuesday that the payments generated revenue of about $200 million in 2003. The company, the second-largest brokerage after Marsh & McLennan Cos., said it?s cooperating with the inquiries.