(Bloomberg) Aon Corp., the world?s second- largest insurance broker, said the US Department of Labor sent the company a subpoena seeking information about its employee benefits business.

The subpoena, received in early February, requests details on compensation arrangements within the business, Chicago-based Aon said in its annual filing with the US Securities and Exchange Commission. Marsh & McLennan Cos., the biggest insurance broker, received a similar request last month.

The Labor Department inquiry builds on state probes examining whether the company steered clients to insurers that paid hidden fees. Aon this month agreed to pay $190 million to settle accusations from New York Attorney General Eliot Spitzer and prosecutors in Connecticut and Illinois. It didn?t admit or deny any wrongdoing.

Aon said it?s cooperating with the Labor Department investigation. Spokesman Al Orendorff didn?t return a phone call seeking further comment.