By Anastasia Moloney

BOGOTA (Thomson Reuters Foundation) - Every day 33 people become entrapped in sex trafficking rings in Guatemala, including a "shocking" proportion of children, some of them sold into the sex trade by their mothers, the United Nations Children's Fund (UNICEF) said.

Nearly 60 percent of the 50,000 victims of sex trafficking in Guatemala are children, according to a report by UNICEF and the U.N. Commission against Impunity in Guatemala (CICIG), which estimates the industry to be worth $1.6 billion a year.

"We never imagined the magnitude of the number of children being sexually exploited. People were shocked by the figures, as were we," Kagoshima said, referring to the recent U.N. report.

Girls as young as 12 work in brothels and are forced to have sex with up to 30 customers a day, while virgin girls are recruited at schools, she said.

Sex trafficking is fueled by a "social tolerance" of children being sold for sex work, a business equal to 2.7 percent of Guatemala's gross domestic product, she said.

"Society collectively closes its eyes to children being exploited. We have to open our eyes to the problem," Kagoshima told the Thomson Reuters Foundation late on Tuesday.

Poverty is one of the biggest drivers of sex trafficking in the central American country where three in five people live on less than $3.10 a day, UNICEF said.

Traffickers often target poor, uneducated and unemployed women and girls, luring them with false promises of earning money as a waitress or model, UNICEF said.

DOMESTIC VIOLENCE

Guatemala's engrained macho culture, along with widespread sexual abuse in the home, also fuels trafficking.

"Often human trafficking starts from domestic and sexual violence by fathers and stepfathers. This is a very common scenario in Guatemala," Kagoshima said.

She said such violence prompts boys and girls to run away from home, leaving them prey to sexual exploitation by traffickers.

The U.N. report cited the case of Claudia, who was caught in a sex trafficking ring aged 12 after leaving home to escape abuse by her stepfather.

"For months, Claudia endured the touching, until the stepfather threatened her one day of abusing her little sister if she would not have sex with him," the report said.

"She accepted to have sex to save her little sister but she was unable to tolerate the situation for long," it said.

Mothers who are known to sell their children into the sex trade are often themselves victims of trafficking or domestic abuse.

"They go to car parks where there are trucks and sell their daughters for a very low price," Kagoshima said.

The report gave the example of Juanita, who at 14 was sold by her mother in 2011 for $13,000 to a policeman who kept her captive as a sex slave for nearly a year.

"I said I didn't want to do anything with him ... he threatened me with a gun and he said "well, you have to do it," the report quoted Juanita as saying.

Guatemala has introduced several initiatives and laws to tackle human trafficking.

These include a 2009 anti-trafficking law, a protocol implemented in 2014 to guide officials when assisting victims, and greater focus on combating the online child sex trade.

Despite these efforts, there are just two prosecutors working on sex trafficking cases across the country, and the number of trafficking convictions in Guatemala remains low, the U.N. report said.

In 2014, the Guatemalan authorities convicted 20 human traffickers, according to the 2015 U.S. State Department report on human trafficking.

"Only 1,600 sex trafficking cases are detected a year. The rest are kept in the dark," Kagoshima said.

(Reporting by Anastasia Moloney, editing by Katie Nguyen.; Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, corruption and climate change. Visit http://news.trust.org)