Aetna Inc. (AET) and Cigna Corp. (CI), two of the largest U.S. health insurers, Friday said they received subpoenas as part of the New York attorney general's investigation into fees insurers pay brokers as an incentive.

The insurers join several others recently subpoenaed by the attorney general, Eliot Spitzer (search), who is investigating whether the fees insurers pay brokers to sell their products constitute a fair business practice or pose a conflict of interest.

Hartford, Conn.-based Aetna was subpoenaed this week, spokesman David Carter said, and intends to cooperate fully.

Philadelphia-based Cigna was also subpoenaed this week, and will cooperate, spokesman Wendell Potter said.

Other insurers that have received subpoenas are Chubb Corp. (CHB) and Hartford Financial Services Group Inc. (HIG).

In April, the three largest insurance brokers -- Marsh & McLennan Cos. (MMC), Aon Corp. (AOC) and Willis Group Holdings Ltd. (WSH) -- said they received subpoenas from Spitzer.

Spitzer's office was not immediately available for comment.

Aetna shares closed Thursday at $84.06 on the New York Stock Exchange (search). They have risen 31 percent in the last year. Cigna shares closed on the Big Board at $68.88. They have risen 39 percent in the last year. The stock market was closed Friday for former President Reagan's funeral.