Popular classified ad website Craigslist has come under fire for profiting off of illegal prostitution ads. While Craigslist executives insist that they screen ads posted to their "adult services" section, police and anti-human trafficking advocates say the site has become a hotbed for online prostitution, which often involves underage women forced into the sex trade. "Craigslist is like the Walmart of online sex trafficking right now in this country," Andrea Powell of the anti-human trafficking group The FAIR Fund tells CNN. When CNN reporter Amber Lyon confronted Craigslist founder Craig Newmark in a surprise interview, Newmark insisted that the company does "more than anyone" to combat prostitution ads, but was soon rendered speechless by her follow-up questions. "In contrast with the epidemic numbers often cited for the nation as a whole," says Craigslist CEO Jim Buckmaster in response to Lyon's report, "the incidence of such crimes is low and getting lower on Craigslist because of the comprehensive preventive measures we have taken." To truly stop this horrific problem, says executive director of the Rebecca Project for Human Rights Malika Saada Saar in CNN, Craigslist must "shut down the adult services section until it can create a comprehensive surveillance and monitoring system that ensures children are not being bought and sold for sex." Watch Amber Lyon's interview with Craig Newmark below: