PORTLAND — The state is looking into whether Maine’s largest health insurer acted improperly in its board elections last month.

Blue Cross and Blue Shield of Maine passed out proxy statements to its 1,500 employees and asked them to vote for open director seats. A letter from Blue Cross President Andrew “Mickey” Greene accompanied the ballots.

The insurer stated it took the unusual step to derail what it feared were plans by opponents to gain a voice on the board at the company’s annual meeting on April 9 in South Portland.

That campaign never materialized.

The state’s Bureau of Insurance cleared the insurer of any wrongdoing, but a day after its finding was made public, the agency received an anonymous complaint from “a concerned employee.” The employee charged that workers in the company’s claims area were coerced to vote by a supervisor.

“The complaint raises serious concerns that management may have gone beyond `asking,”‘ Brian Atchinson, Maine’s insurance superintendent, wrote Monday to Attorney General Andrew Ketterer.

Blue Cross stated it was unaware of the complaint. It repeated its position that workers were only asked to vote and were under no pressure to cast ballots for particular candidates.

But Carol Morris, a company spokeswoman, acknowledged that a supervisor may have been overzealous.

“It’s possible that a supervisor could have done something that wasn’t the intent of the company,” she said.

Blue Cross is a not-for-profit corporation with 480,000 members. Some of its recent business decisions have angered community groups.

A plan to team up with Maine Medical Center to develop a for-profit health maintenance organization called Maine Partners Health Plan was criticized by consumer activists as potentially monopolistic. Maine’s insurance superintendent is expected to decide whether to approve the HMO sometime next month.

The company also has floated the idea of converting from a nonprofit to a stock or mutual company.

Proxy statements allow members to vote for officers without actually attending an annual meeting.