WASHINGTON — Gun homicides have dropped steeply in the United States since 1993, a pair of reports released Tuesday showed, adding fuel to Congress’ battle over whether to tighten restrictions on firearms.

A study released Tuesday by the government’s Bureau of Justice Statistics found that gun-related homicides dropped from 18,253 in 1993 to 11,101 in 2011. That’s a 39 percent reduction.

Another report by the private Pew Research Center found a similar decline by looking at the rate of gun homicides, which compares the number of killings to the size of the country’s population. It found that the number of gun homicides per 100,000 people fell from 7 percent in 1993 to 3.6 percent in 2010, a drop of 49 percent.

Both reports also found the rate of non-fatal crimes involving guns was also down by around 70 percent over that period.

The trend in firearm-related homicides is part of a broad nationwide decline in violent crime over past two decades, including incidents not involving firearms.

The Justice study also said that in 2011, about 70 percent of all homicides were committed with a firearm, mainly a handgun.

The data was released three weeks after the Senate rejected an effort by gun control supporters to broaden the requirement for federal background checks for more firearms purchases. Senate Democratic leaders have pledged to hold that vote again, and gun control advocates have been raising public pressure on senators who voted “no” in hopes they will change their minds.

Gun rights advocates have argued that people are safer when they are allowed to own and carry guns. Those supporting gun control say that with more background checks, gun violence would drop because more criminals and mentally unstable people would be prevented from getting weapons.