NEW YORK (Bloomberg) — Marsh & McLennan Cos. is among the companies subpoenaed by Connecticut Attorney General Richard Blumenthal in an investigation of possible collusion in the reinsurance industry.

Blumenthal's office demanded records from Marsh & McLennan's Guy Carpenter unit in late 2006, the New York-based company said in a regulatory filing late last week.

Blumenthal may pursue civil claims against Guy Carpenter, the filing said. Marsh & McLennan, the world's largest insurance brokerage, said it is cooperating with the investigation.

Blumenthal subpoenaed at least 20 companies in a probe into possible anticompetitive practices that began last year.

In July, Hartford Financial Services Group Inc. said it was subpoenaed for records about "reinsurance facilities," or arrangements in which reinsurers pool their resources to provide coverage to insurance companies.

Blumenthal declined to name the companies.

Marsh & McLennan spokeswoman Christine Walton declined to comment.

Hartford exited the reinsurance business in 2003. The company said in July it was cooperating with Blumenthal's office.