By Jonathan Stempel

(Reuters) - A federal appeals court on Wednesday said a Fort Wayne, Indiana bus system was wrong to refuse to post an ad from a women's health service on its buses after learning that the group opposed abortion rights.

The 7th U.S. Circuit Court of Appeals in Chicago said the ad from Women's Health Link was "innocuous," and the decision by the Fort Wayne Public Transportation Corp, or Citilink, to reject it was unconstitutional censorship.

Wednesday's 3-0 decision reversed a Jan. 5 ruling by U.S. District Judge Robert Miller in Fort Wayne, and directed that Citilink accept the ad in question.

Many public transport providers face lawsuits challenging ad limits that critics say amount to viewpoint discrimination, and violate advertisers' free speech rights.

Mark Baeverstad, a lawyer for Citilink, said his client is disappointed in the decision and will review its options.

The ad featured a woman's face, the copy "You are not alone. Free resource for women seeking health care," and the website, phone number and logo for Women's Health Link.

Upon learning that the group provides services to women who carry their babies to term, Citilink decided that the ad ran afoul of its ban on public service ads advocating positions on political, religious, or moral issues.

Writing for the appeals court, however, Circuit Judge Richard Posner said Citilink's ad censorship policy is limited to ad content, and the Women's Health Link ad lacked "the faintest suggestion" of a political, religious or moral agenda.

"We know that Health Link is pro-life, but nothing in the ad reveals that," Posner wrote. "Citilink's refusal to post the ad was groundless discrimination against constitutionally protected speech."

The plaintiff was represented by Alliance Defending Freedom, a conservative advocacy group. A lawyer for ADF did not immediately respond to a request for comment.

(Reporting by Jonathan Stempel in New York; Editing by David Gregorio)