Responding to a controversial ad campaign that appears to exploits the murder of women in B.C., Prime Minister Paul Martin called them unacceptable.

The billboards, paid for by the U.S.-based People for the Ethical Treatment of Animals, went up in Toronto and Edmonton this week.

Designed to promote PETA's anti-meat campaign, the larger-than-life billboard shows the face of a haggard young woman on one side and a pig's face on the other. Between the two is the blunt slogan: "Neither Of Us Is Meat."

Interpreted as a reference to the case of Robert Pickton, the B.C. man charged in the deaths of 15 women on his farm, the campaign has sparked condemnation from victims' families.

Martin has joined the chorus of criticism. Describing his revulsion at the campaign, the PM said there may be ways to support a cause, but this isn't one of them.

"Those ads are simply unacceptable,'' Martin said in Quebec.

"When you think of the terrible, terrible trauma that affected all of those women in British Columbia, when you think of what those families are going through right now -- that kind of publicity is just not acceptable.''

In response, PETA said, "We can't imagine that Mr. Martin has seen the ad, since the ad clearly represents both humans and other animals as deserving of our respect and empathy.''

Marylynne Craft, whose daughter Cindy Felix is listed among the murders that Pickton is charged with, says she's furious.

"It makes me sick to my stomach," she told CTV News. "It doesn't exactly say 'Vancouver prostitute' and 'Pickton pig.' But is might as well."

The Advertising Council of Canada, which does not pre-screen print ads, says it takes formal complaints from the public to kickstart censure of controversial advertising.

PETA has made a name for itself since its founding in 1980 for its shock-value ad campaigns denouncing the eating of meat and other animal foods. The group enraged residents in Des Moines, Iowa a decade ago when it ran ads in local newspapers comparing meat eaters to convicted serial killer Jeffrey Dahmer.

Late last year, the animal rights activists tried to run an advertisement in a Vancouver newspaper linking the slaughter of animals and acts of violence against people.

Family of the victims expressed their disgust at the time, prompting two newspapers to refuse to run the ads.