The Mayors Against Illegal Guns study found 10 U.S. states sold 57 percent of all firearms used in crimes in other states last year, The Washington Post said Friday.

Among those 10 states were Virginia and West Virginia, the study underwritten by 300 U.S. mayors said.

Those 10 states with the highest crime-gun export rates in the nation last year also had higher gun homicide rates than the 10 states with the lowest export rates.

The study, based on Bureau of Alcohol, Tobacco, Firearms and Explosives data, found those top 10 states saw nearly 70 percent more gun homicides than their bookend counterparts in 2007.

The study found that in those states that require background checks for all handgun sales at gun shows the export rate was less than half the national average.

All states' rankings on the study's lists were not identified by the Post, nor was the study's margin of error.