(Bloomberg) Aon Corp., one of the insurance brokers subpoenaed in New York Attorney General Eliot Spitzer's investigation of alleged kickbacks and bid-rigging, said some employees hadn't followed the company's code of conduct.

“The vast majority of our employees adhere to the longstanding principles embodied in our code of conduct and Aon values,” Aon chief executive officer Patrick Ryan said in a statement. “However, we have found indications that some employees have not always followed these principles.”

Aon spokesman Gary Sullivan said an internal investigation is under way and “appropriate action” will be taken against the employees once it's done. He declined to identify the employees or say how many were involved.

Spitzer sued Marsh & McLennan Cos., the world's biggest broker, in October, accusing it of improperly taking incentive fees from insurers and fabricating insurance bids.

Marsh as well as Aon and Willis Group Holdings Ltd., its biggest competitors, banned the fee arrangements after the suit. Aon hasn't been sued by Spitzer.

Aon shares fell 34 cents to $21.92 at 3:24 p.m. in New York Stock Exchange composite trading. Aon's statement was in response to an article in the Chicago Tribune yesterday that was titled “Aon chief not fazed by insurance probes.” Ryan said the characterisation was inaccurate.