Lil Boosie -- Massive Alleged Concert Scam Sweeping Country

Lil Boosie is putting concert venues everywhere on notice -- telling TMZ, a massive Boosie concert scam is currently preying on unsuspecting booking agents across the country ... and several people have already fallen victim.

We spoke to several of the alleged victims -- two in Dallas and one in Detroit -- and each of them claim the scam cost them $25,000.

Here's how it happened -- one of the alleged victims LaToya Thompson tells us, she came across a Boosie booking flier on Instagram recently and called the phone number. She says she was eventually put in touch with a man claiming to be Boosie's brother TQ.

LaToya tells us, "TQ" instructed her to wire him $25,000 to book Boosie for a concert in April -- and as soon as the money went through last week, "TQ" went AWOL.

The two other alleged victims tell the same story -- one says he had booked Boosie for an appearance last week, and the rapper never showed. He says "TQ" also never responded to his phone calls.

LaToya sent us the contract -- which lists a Giovany Productions as the company behind the bookings. We tried to get in touch with someone at Giovany but the phone numbers didn't work.

But Boosie says it doesn't matter -- he never gave permission to any company to book him. All bookings must go through his brother TQ -- the real TQ -- and TQ tells us, he was NOT involved in the bookings in question. TQ also says he plans to file a police report.