A federal investigator says fake IRS agents have targeted more than 366,000 people with harassing phone calls demanding payments and threatening jail time as part of a huge nationwide scam.

A deputy inspector general for the agency says more than 3,000 people have fallen for the ruse since October 2013. He says they have been duped out of a total of $15.5 million.

In testimony before Congress Thursday, Timothy Camus said it is the largest scam of its kind in the history of the agency. Camus said people in every state have been targeted.

He said two people in Florida have been arrested. They were accused of being part of a scam that involved people in call centers in India contacting U.S. taxpayers and pretending to be IRS agents.

(AP)