Clear Channel, the outdoor advertising giant, said Friday that it was a mistake to sell space on dozens of Cleveland and Columbus billboards warning that “voter fraud is a felony" — many in African American neighborhoods — to an anonymous foundation.

But the company also said it has no plans to take the ads down.

Civil rights and labor groups have denounced the billboards, which also feature a giant judge’s gavel and a warning of “up to 3 1/2 years and a $10,000 fine,” as an attempt to intimidate minority voters. The ads are appearing in Milwaukee as well, according to Clear Channel.

The purchaser of the space remains anonymous, described at the bottom of the ads only as a “Private Family Foundation.“

Jim Cullinan, vice president of marketing and communications for Clear Channel Outdoor, said that if the ad is accurate and is not “an attack ad,” the company will sell the space. He added that Clear Channel usually requires that ads have the name of the purchaser at the bottom.

“Honestly it was a mistake of the specific sales person who agreed to that,” Cullinan said. “But once we put them up and signed a contract, we had to live with the anonymity. We understand there’s people upset. We’re working with the community.”

Ohio has long been a battleground for legal disputes over election issues such as early voting and provisional ballots. Secretary of State Jon Husted and Attorney General Mike DeWine, both Republicans, have been accused of pursuing policies and regulations designed to suppress black votes.

Mike Gillis, communications director for the Ohio AFL-CIO, said the location of the ads is “clearly by design.”

“They’re really designed to scare people,” he said.

In a statement, AFL-CIO Executive Vice President Arlene Holt Baker and Ohio AFL-CIO Secretary Treasurer Pierrette “Petee” Talley called on Clear Channel to pull the ads.

“Every election year we see offensive, underhanded tactics by groups who don’t want everyone to have access to the voting booth,” they said. “This year, intimidating billboards that point out voter fraud are appearing in predominantly African American communities in Ohio, despite little to no evidence that voter fraud exists. ... We urge Clear Channel to remove these billboards and replace them with information that will help voters exercise their fundamental right to vote in this year’s critical election.”