Phony "DEA" Drug Scam Under Investigation

A downright terrifying, diabolical scam targeting Americans who buy prescription drugs online is being investigated by the Drug Enforcement Administration ... TMZ has learned.

A number of Americans have been victimized over the last year ... but the best way to tell this story is by example. A Hollywood producer received a message (below) on his cell phone last week from a man claiming to work for the DEA, saying he needed to speak with the producer urgently -- adding the producer had been indicted on drug charges.

The producer freaked out and called his lawyer, who got in touch with the alleged DEA agent by phone. The "agent" said the producer had been indicted in the Dominican Republic, for allegedly illegally purchasing one bottle of Xanax online 5 years ago -- the website was registered in the Dominican Republic.

After several calls, the agent told the lawyer there might be a way to "make the case go away," because one of the judges on the Supreme Court in the Dominican Republic would dismiss the case if the producer paid a civil penalty. That made the lawyer suspicious enough to tape the next call and turn over the info to the DEA.

DEA officials tell us ... multiple scammers are posing as agents, using the names of actual DEA agents.

The DEA is hot on the trail. A DEA official tells TMZ ... they've received numerous complaints from victims over the last year, most involving threats of prosecution based on the purchase of online prescriptions.

We're told the likelihood is ... a number of people folded like a cheap suit when they received the call threatening prosecution and sent the money in, hoping the criminal case would go away.