BUENOS AIRES, Argentina – Argentina’s government is banning prostitution ads in newspapers and other mass media as of today, saying it is combatting violence against women.

The ban decreed by President Cristina Fernandez drew strong praise from women’s groups and the U.S. ambassador, who has made reducing sex trafficking a key goal of her tenure in Argentina.

But some of the president’s opponents fear it may be used to punish opposition media this election year by removing an independent source of revenue for an industry that in many cases depends on official advertising, a flow of revenue that press freedom groups say has been unequally directed toward the government’s supporters.

The decree bans any written messages or images that “promote the exploitation of women,” including those that “abuse, defame, discriminate, dishonor, humiliate or threaten the dignity of women.”

Also outlawed are overtly pornographic messages and images of women, children and girls, which the president said serve to legitimize unequal treatment and violence against women.

U.S. Ambassador Vilma Martinez wrote an open letter to Fernandez praising her fight against trafficking in women and girls.

“Many countries will appreciate seeing the effects that this decree will bring in the fight against this crime,” Martinez said.

“The press has to be conscious of its position as formers of public opinion,” said Susana Trimarco, who has campaigned against sex trafficking in Argentina since her daughter was kidnapped in 2002 and apparently disappeared into the sex trade.

“I always thought it strange that the first pages should have stories about the crime of sex trafficking, and those in the end should have advertisements offering sex for money,” Trimarco said.

The ban is taking effect even though its sanctions aren’t yet specified. Argentina’s justice and human rights ministry is tasked with developing regulations to implement the ban. The decree also creates a monitoring office to track advertisements nationwide and warn newspapers to remove offending ads.

Fernandez specifically took aim at the newspaper Clarin, a frequent antagonist. She cited the opposition paper’s Area 59 section as particularly unethical. Area 59 has included columns of ads for escorts, “gym teachers” “massage therapists” and “underwear models” offering “pleasures without limits.” Until now.