Massachusetts welfare officials and local law enforcement are teaming up with the feds to crack down on trafficking of Supplemental Nutrition Assistance Program benefits, formerly known as food stamps.

Until now, local law enforcement had the power to go after food stamp recipients engaging in fraud, but not retailers. This agreement gives them that authority.

James Arena-DeRosa is with the U.S. Department of Agriculture, which oversees the food stamp program.

“We are pleased to be working with the Department of Transitional Assistance and Law Enforcement Officials toward the common goal of ensuring that taxpayer’s dollars are used for the intended purpose of providing healthy foods to people in need,” Arena-DeRosa said Monday.

SNAP benefits cannot be converted to cash and can only be used to purchase groceries.  But some merchants pay recipients cash for their cards, sometimes for pennies on the dollar.  And then the store redeems the card at face value, pocketing the profit.

The USDA will provide local law enforcement with decoy benefit cards to use in undercover investigations of retailers suspected of trading cash for food stamps.

So far, local police departments in Everett, Taunton, Addleborough and Pittsfield have signed up for the program.