A network of nuns has ditched their habits to dress like prostitutes and infiltrate brothels worldwide in an effort to rescue victims of sex trafficking and buy children sold into slavery.

The group of 1,100 religious sisters, known as Talitha Kum, currently works undercover in brothels in at least 80 countries, helping to free victims of sex trafficking and slavery.

John Studzinski, the investment banker and philanthropist who chairs Talitha Kum, said the group is looking to expand its reach to 140 countries, according to Reuters.

"These sisters do not trust anyone," Studzinski, a vice chairman of The Blackstone Group, recently told the Trust Women Conference on women's rights and trafficking hosted by the Thomson Reuters Foundation.

"They do not trust governments, they do not trust corporations, and they don't trust the local police. In some cases they cannot trust male clergy," he said in a Nov. 18 speech. "They work in brothels. No one knows they are there."

"They work in brothels. No one knows they are there."

- John Studzinski, Talitha Kum

Studzinski said the secret group of sisters -- founded in 2004 -- goes to great lengths to rescue victims, often dressing up as sex workers and walking the streets.  

"I'm not trying to be sensational, but I'm trying to underscore the fact this is a world that has lost innocence ... where dark forces are active," he told the conference. "These are problems caused by poverty and equality, but it goes well beyond that." 

Studzinski cited egregious cases of trafficking and slavery, including the story of a woman forced to have sex with 10 men at the same time, Reuters reported.

He also said Talitha Kum -- which translated from Aramaic means arise child -- raises money to buy children who are sold into slavery by their parents in places like Africa, the Philippines, Brazil and India.

"This is a new network of houses for children around the world who would otherwise be sold into slavery. It is shocking but it is real," Studzinski said, according to Reuters.

But not all anti-trafficking groups agree with the work of Talitha Kum.

Christina Arnold, founder and CEO of Prevent Human Trafficking, said the group of sisters, while well-intentioned, "may be doing more harm than good."

"When you the buy the victim, you just drive up the cost for brothel owners or traffickers trying to sell in the future," Arnold told FoxNews.com Tuesday.

"It sounds like a good idea but it's actually a ludicrous one," said Arnold, who spent many years living in southeast Asia, including Thailand, which she described as the "epicenter" for human trafficking. 

"People have their hearts in the right place," she added. "But are these nuns going to go into fishing boats? Because that's where the biggest number of slave traffickers are right now."

"The majority of trafficking is labor trafficking," Arnold said.

There are conflicting figures on the number of people trafficked each year in the world. According to Reuters, Talitha Kum reports that 73 million people, roughly 1 percent of the world's population, are trafficked in some form -- a number Arnold disputes.

According to the International Labor Organization, nearly 21 million people are victims of forced labor – 11.4 million women and girls and 9.5 million men and boys. Almost 19 million victims are exploited by private individuals or enterprises and more than 2 million by the state or rebel groups. Of those exploited by individuals or enterprises, 4.5 million are victims of forced sexual exploitation, according to ILO.

"Human trafficking is modern-day slavery and is a worldwide phenomenon," Robyn Shepherd, a spokeswoman for Amnesty International, told FoxNews.com.

"Victims are trafficked into a range of hazardous labor including farm work, sweatshops, domestic servants, forced prostitution and are subjected to sexual abuse and other forms of violence," Shepherd said. "Trafficking is a fundamental abuse of human rights and includes the abuse of the rights to: physical integrity, life, liberty, security of person, dignity, freedom from slavery, torture, and other inhuman or degrading treatment."