WASHINGTON — Nearly 600 mayors nationwide, led by Mayor Michael R. Bloomberg of New York and other city leaders, are mounting a new campaign to identify states with lax gun laws and push for tighter restrictions to prevent the trafficking of guns used in crimes.

A study due to be released this week by a coalition called Mayors Against Illegal Guns uses previously unavailable federal gun data to identify what it says are the states that most often export guns used in crimes across state lines. It concludes that the 10 worst offenders per capita, led by Mississippi, West Virginia and Kentucky, supplied nearly half the 43,000 guns traced to crime scenes in other states last year.

The study also seeks to draw a link between gun trafficking and gun control laws by analyzing gun restrictions in all 50 states in areas like background checks for gun purchases, policies on concealed weapons permits and state inspections of gun dealers. It finds that, across the board, those states with less restrictive gun laws exported guns used in crimes at significantly higher rates than states with more stringent laws. An advance copy of the study was provided to The New York Times.

“There are 12,000 gun murders a year in our country, and this report makes it perfectly clear how common-sense trafficking laws can prevent many of them,” said Mr. Bloomberg, who is the co-chairman of the coalition with Mayor Thomas M. Menino of Boston. “For mayors around the country, this isn’t about gun control. It’s about crime control.”