Gun trafficking and the straw purchasing of firearms would become federal crimes under bipartisan legislation announced by five senators Monday.

Senate Judiciary Committee chairman Patrick Leahy, D-Vt., said the bill would establish tough penalties for those who buy a firearm or ammunition with the intent of transferring it to someone else. The measure would also make it a crime to smuggle firearms out of the United States.

Leahy said there is no federal law now that defines either gun trafficking or straw purchasing -- when a person who can legally buy guns transfers those guns to criminals and others barred from gun ownership -- as crimes.

The bill was crafted by Leahy, fellow Democrats Dick Durbin of Illinois and Kirsten Gillibrand of New York, and Republicans Mark Kirk of Illinois and Susan Collins of Maine.

"The absence of any federal law defining gun trafficking as a crime in this country is shocking," Gillibrand said.

The legislation will be taken up by the Judiciary Committee on Thursday as part of a package of four bills aimed at reducing gun violence. The others involve regulating assault weapons, enhancing school safety and requiring background checks for all firearm sales.

The Judiciary Committee has taken a lead in considering the gun violence issue following the school shootings last December in Newtown, Conn.

The proposed legislation would make it a crime to transfer a weapon when a person has "reasonable cause to believe" that the firearm will be used in criminal activity. It contains exemptions for the transfer of a firearm as a gift, or in relation to a legitimate raffle or contest.

While existing law makes it a crime to smuggle firearms into the United States, the Senate proposal would also ban the smuggling of weapons out of the United States. That provision is specifically aimed at the trafficking of arms across the Southwest border.