Minneapolis leaders, stirred by recent arrests and disturbing stories of teenage girls swept from city streets and sold for sex on a popular website, on Thursday called upon the owner of Backpage.com to stop running exploitative ads that enable juvenile prostitution.

City Council members unanimously approved a resolution demanding that New York-based Village Voice Media end its "adult services" section of Backpage.com. Minneapolis police report that all 20 child sex-trafficking cases they have investigated so far this year involve juvenile victims being prostituted on this website.

Advocates say the sex trafficking of young girls in the Twin Cities is on the rise. Vednita Carter, founder and executive director of Breaking Free, an organization that helps victims of abuse and commercial sexual exploitation, said more than 70 girls under 18 came to seek help in the past year, up from about 50 or so in the past year and around 25 in years past. She said that about 40 percent of them said they had been advertised on Backpage.com.

On Thursday, police arrested a man they say approached two runaway girls, 15 and 17, in downtown Minneapolis early last month and turned them into prostitutes, advertising them as a "two-girl special" on Backpage.com, according to a criminal complaint. A day earlier, a New Jersey man was sentenced in federal court to eight years in prison after taking a 16-year-old he met outside a Minneapolis nightclub to Colorado, where she was advertised online and set up for prostitution in a hotel room.

Liz McDougall, general counsel for Village Voice Media, said she thinks it's good that the resolution calls for action but also calls for significant preventive measures. She said that the company works on many levels to stop trafficking on the site and cooperates regularly with law enforcement. Shutting the site down would only move such operations offshore, where U.S. officials wouldn't be able to recover the digital and financial clues to make arrests and conduct investigations, she said.

She added that charging for adult services ads allows the site to have credit card information, which she said is the most reliable tool in tracking down the people exploiting children. If they made the section free, it would only increase use and cause the loss of valuable evidence.

"Backpage has been targeted, and it's been a politically popular thing to do, but in doing so, [officials] are missing out on the big picture of human trafficking," she said.

After the full City Council ratifies the resolution Aug. 17, Minneapolis will join other major cities -- including St. Paul, which passed a similar resolution in July -- that have condemned the site for its role in the sex trafficking of young people.

Battle plan outlined

Assistant Police Chief Jane Harteau and City Attorney Susan Segal also told council members Thursday about their interdepartmental plan to combat the sexual exploitation of minors. The Legislature passed the Safe Harbors law last year, which requires law enforcement to treat sexually exploited youth under 16 as victims, not criminals.

"It's really opened our eyes to this issue that's hidden, that's online, that's happening right here," Segal said. She said runaway teens are approached about getting into prostitution within 24 hours of leaving home.

They said city officials are meeting with nonprofits, other law enforcement agencies, attorneys and businesses -- including hotels, where many victims meet with clients -- to improve collaboration.

Harteau said the police department assigned an investigator at the beginning of the year to work on juvenile sex trafficking cases. Since January, the department has received 60 tips of possible sex trafficking, including 20 that led to investigations. Their priorities for the project are to rescue victims, arrest perpetrators and get the message out about the issue, Harteau said. Nine people have been charged so far this year in cases involving juvenile sex trafficking. Among those charged is one child-prostitution client.

"This is a victim-centered project," Harteau said.

The FBI identifies Minneapolis as one of 13 cities with a large child prostitution concentration. Still, quantifying sex trafficking can be difficult, said Mary Beth Hanson, communications director of the Women's Foundation of Minnesota, which runs Minnesota Girls Are Not For Sale, a campaign addressing the prostitution of underage girls in the state.

"It's illegal, and because of that, it's deeply hidden," Hanson said.

Hanson said many of the girls are constantly moved around the country, which makes it difficult to track them. Pimps target girls who they know are vulnerable and will use threats and drugs to keep them compliant.

The girls are forced into the work, so it can't be called a choice by any means, Carter said. "We know that little girls don't dream about becoming prostitutes," she said.

Recent cases tied to website