WASHINGTON — Federal authorities have taken down Backpage.com, a major classified advertising website that has been repeatedly accused of enabling prostitution and sex trafficking of minors.

“Backpage.com and affiliated websites have been seized,” a notice on the website says.

Backpage has been under increasing pressure in recent years, in part because it featured ads that included what child advocates said were code words for underage girls, including “Amber Alert.”

In January 2017, the site shuttered its “adult services listings” section under mounting criticism from law enforcement groups and senators. But many of the adult listings were simply rerouted to sections of the site dedicated to dating.

Revenue at Backpage increased to $135 million in 2014 from $5.3 million in 2008, according to a Senate report last year. More than 90 percent of the earnings came from adult ads, the California Department of Justice found.