WASHINGTON (AFP) - US states with lenient gun laws suffer most from fatal shootings of police officers and handgun killings, and are the main source for weapons used in out-of-state crimes, according to a study released Friday.

The report by Mayors Against Illegal Guns, a bipartisan coalition of over 300 US mayors, found that 10 states supplied 57 percent of guns found in crimes committed in other states in 2007. Georgia was the biggest interstate crime gun supplier in a list that also included Florida, Texas and Virginia.

"Our analysis shows quite clearly that states that are the top sources for crime guns have weak gun laws," said New York City Mayor Michael Bloomberg, co-chair of the group.

Some 141,577 guns crossed state borders last year, of which at least 42,450 guns were used in crimes, according to data from the Bureau of Alcohol, Tobacco and Firearms (ATF).

Virginia, adjacent to the US capital, ranked fourth with 2,261 weapons used in crimes in other states. Some 975 gun crimes took place in Washington, DC, where the US Supreme Court recently overturned a handgun ban.

"The fact that so many illegal guns come from out of state highlights the need to work cooperatively at a national level to ensure that our local police officers have the necessary information to track and document interstate illegal gun trafficking," said Boston Mayor Thomas Menino, co-chair of the coalition.

The report also found that the 10 states with the highest export rates for crime guns had 59 percent higher gun murder rates than the 10 states with the lowest crime gun export rates.

States with high-export rates also saw almost three times more fatal shootings of police officers.