A group of 18 states' attorneys general is calling on Craigslist to drop the "adult services" section of the popular classified site, claiming that the company has failed to live up to its commitment to police its listings for illicit ads linked to prostitution and other criminal activity.

"Only Craigslist has the power to stop these ads before they are even published, and sadly they are completely unwilling to do so," Kansas Attorney General Steve Six said in a statement.

In a letter to Craigslist CEO Jim Buckmaster and founder Craig Newmark, the attorneys general charged that Craigslist remains home to ads facilitating prostitution and human trafficking, despite promises to clean up the site.

In November 2008, under mounting pressure from law enforcement authorities, Craigslist reached an agreement with 40 states' attorneys general to implement new filtering and verification tools in an effort to weed out illicit ads.

In the meantime, Craigslist has remained in the spotlight as critics contend that it remains a popular forum for selling sexual services, sometimes involving minors.

The company drew an unwelcome batch of publicity last spring when Philip Markoff, a 23 year-old medical student, allegedly shot and killed a masseuse he met answering an ad in the erotic services section of Craigslist.

Markoff, who was quickly branded the "Craigslist killer," was also implicated in a separate armed robbery and assault of women he had also met through the site. He committed suicide in his jail cell in Boston last week.

Connecticut Attorney General Richard Blumenthal, who led the coalition of states that reached the 2008 agreement with Craigslist, has since voiced his disappointment with the company's follow-through. In May, he issued a subpoena seeking documents related to Craigslist's efforts to police its site.

"Craigslist clearly lacks the wherewithal -- or will -- to fight flagrant prostitution ads that persist on its site," Blumenthal said Tuesday in a statement calling for the shutdown of the adult services section.

Last May, on the heels of Markoff's arrest and seven months after reaching the initial agreement, Blumenthal began making noise about Craigslist's failure to cooperate, threatening legal action if the company did not take steps to purge its listings of criminal activity. In response, Craigslist dropped the "erotic services" section of the site, renaming it "adult services" and pledging to implement a manual review of the listings.

In a statement e-mailed to InternetNews.com, Craigslist said it will continue to work with the attorneys general, but declined to address their charges directly.

"We strongly support the attorneys general desire to end trafficking in children and women, through the Internet or by any other means," the company said. "We hope to work closely with them, as we are with experts at nonprofits and in law enforcement, to prevent misuse of our site in facilitation of trafficking, and to combat such crimes wherever they appear, online or offline."

CEO Buckmaster also addressed the company's manual review process in a blog post last week.

Buckmaster claimed that since Craigslist implemented the procedure last May, every listing submitted to the adult services section has been reviewed by an attorney, resulting in the rejection of more than 700,000 ads in the first year. He also pointed to other sites, including eBay's network of classified sites and Village Voice Media's backpage.com, that have laxer enforcement standards and appear to actively court ads for sexual services.

"Our uniquely intensive manual screening process has resulted in a mass exodus of those unwilling to abide by Craigslist's standards, manually enforced on an ad-by-ad basis," Buckmaster said. "Manual screening matters."

But in their letter this week, the attorneys general accused Craigslist of falling short of its pledge.

"Your much-touted 'manual review' of adult services ads has failed to yield any discernible reduction in obvious solicitations," they wrote.

"We recognize that Craigslist may lose the considerable revenue generated by the adult services ads," they said. "No amount of money can justify the scourge of illegal prostitution -- and the suffering of the woman and children who will continue to be victimized -- in the market and trafficking provided by Craigslist."

Kenneth Corbin is an associate editor at InternetNews.com, the news service of Internet.com, the network for technology professionals.