Victims of sex trafficking could sue U.S. websites that connect customers to them, experts said, as a new law signals a drive by Washington to clamp down on soaring internet sex slavery.

The legislation, passed in April, aims to make it easier to prosecute social media platforms and websites that facilitate sex trafficking, although victims would be required to show that the internet companies did so knowingly.

"If you traffic girls on websites, those girls can come after you," said Jason Matthews, anti-trafficking group ECPAT-USA's public policy director.