A coalition of mayors says several unlicensed Virginia gun dealers were the targets of a campaign aimed at stopping illegal gun sales online.

Mayors Against Illegal Guns released the results of its investigation Thursday showing 62 percent of online dealers nationwide were willing to sell to people who likely couldn't pass a background check. Five of the eight online gun sellers contacted in Virginia made such an agreement, which is a felony under federal law.

The five sellers were located in Charlottesville, Chesapeake, Hampton Roads, Suffolk and Woodstock. They were offering handguns ranging from $360 to $850.

Investigators contacted 125 unlicensed online gun sellers in 14 states, including those on Craigslist. The website prohibits the sale of firearms.

The coalition's "Delete Online Outlaws" campaign reiterates a commitment to closing a loophole that enables criminals and others prohibited from possessing guns to acquire them without having to pass a background check.

According to the U.S. Justice Department, more than 4,000 websites offer guns for sale. An estimated 40 percent of U.S. gun sales are done privately.

"Today, yet another undercover investigation gives us a chilling look into America's illegal gun market," said Boston Mayor Thomas Menino, the coalition's co-chairman. "We have been arguing for years that protecting public safety in our cities requires effective and comprehensive background checks."

The campaign asks the public to urge websites to adopt policies that will help prevent illegal online gun sales. Those policies include requiring sellers and buyers to register with the site before transactions occur, provide a mechanism to flag suspicious behavior in gun sales and remove suspicious ads, and develop rigorous self-policing measures, including "secret shopping," to detect and deter suspicious activity.