By Ellen Wulfhorst

NEW YORK (Thomson Reuters Foundation) - More than 1,000 women and girls have been apparent victims of sex trafficking in illicit cantinas in the United States that largely operate beyond the reach of law enforcement, the anti-slavery group Polaris said on Thursday.

Half of the trafficking cases in cantinas arose in Houston, Texas, a city near the Mexican border with a large Latino population, Polaris said in a study tracking calls to its trafficking hotlines from over the past decade.

Cantinas, social gathering spots popular in Latino communities, may disguise the cost of commercial sex in very high drink prices, and women are forced to flirt and drink with patrons, the study's author Tessa Couture told the Thomson Reuters Foundation.

Cantinas also may limit who enters and may not be open to the general public, the report said.

Overall, hotlines run by Polaris got reports of 201 cases of sex and labor trafficking, involving 1,300 potential victims at cantinas and bars in 20 U.S. states from 2007 to 2016.

More than half the victims were underage, it said.

At one illicit cantina in Houston, some victims were forced to have sex as often as 50 times a day, it said. The cantina owner, convicted of sex trafficking, conspiracy and other charges, was sentenced to life in prison earlier this year.

While cases of trafficking in brothels have been the subject of high-profile prosecutions, only a small number of prosecutions have focused on cantinas, mostly in Houston, the report said.

Cases can be hard to investigate and prosecute because traffickers and owners may hide their ownership of cantinas or liquor licenses, and because victims are too scared to testify in court, afraid that traffickers will retaliate by hurting their families, Polaris said.

"Those organized crime networks reaching back into Mexico and Central America are very real. People know that there's a very real possibility their families will be hurt," Couture said.

Many traffickers are involved in drug cartels or gangs, and victims often were lured to the United States with job offers or other false promises, Polaris said.

Both traffickers and victims in the illicit cantinas tended to be from Mexico or Central America, it said.

The women and girls are intimidated by threats and abuse or forced into deep debt, and most reported being kept isolated, confined and monitored by their traffickers, the report said.

Of those who escaped, a third were helped by potential buyers of sex who found out the victim's circumstances, it said.

Cantina-style cases were reported in California,

Washington, D.C., New York and elsewhere, the report said.

Polaris recommended increased training for law enforcement and service providers such as healthcare workers, better information sharing among law enforcement and government agencies, and more funding for investigations and prosecutions.

(Reporting by Ellen Wulfhorst, editing by Alisa Tang. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, land rights and climate change. Visit http://news.trust.org)