PORTLAND — An opponent of the successful effort to have an elected mayor has filed a formal ethics complaint over nearly $47,000 in free advertising provided to the campaign by The Portland Press Herald.

Jonathan Wayne, executive director of the Maine Commission on Governmental Ethics and Election Practices, on Monday confirmed the agency received the complaint filed by Thomas Valleau. Wayne said it will likely be taken up by commissioners at their February meeting.

At issue are nearly $47,000 in free advertisements given to the Elect Our Mayor/Yes on 1 Political Action Committee in the week leading up to the November City Charter amendment referendum.

Valleau, a former Charter Commission member, claims the Press Herald gave the PAC eight full-page color ads without disclosing its involvement to the city or its readers.

Valleau in a press release said he filed the complaint because he believes Maine election law requires the newspaper to register with the city and disclose the ads as a political contribution.

A campaign finance report listed the Portland Regional Chamber as contributing more than $46,500 in advertising in the Press Herald to the campaign. But a notation said “The Portland Press Herald did not charge the Portland Regional Chamber for the ad space.”

The ballot measure to switch to an elected mayor, who will serve a four-year term and earn an annual salary of $67,000, passed by 1,138 votes, 12,963 to 11,825.

“Newspapers should not donate free advertising to political campaigns that they decide to favor,” Valleau said. “In any event, the public has the right to know who is behind attempts to influence the vote.”

Press Herald Executive Editor Scott Wasser previously said he had no knowledge of the advertising arrangement and defended the newspaper’s coverage of the charter amendment campaign, suggesting opponents were criticizing the newspaper because their side lost.