Published: Aug 14, 2013 5:40 PM EDT
Updated: Aug 14, 2013 6:37 PM EDT

FT. MYERS, Fla. - Lee Memorial Health System has put a ban on accepting large bills after thieves use phoney cash 3 times in as many weeks.

LMHS plans to enforce the ban at least through the end of August.

"Some of the preventative measures that we are taking is that we're no longer accepting $50 or $100 dollar bills at any of our locations. That includes with our billing as well," said Kat Welsch, a spokesperson for the hospital.

According to incident reports filed with the Lee County Sheriff's Office the exchanges happened twice at the Health Park cafetaria, and once at the campus off Doctor's Way near Daniels Parkway.

The crooks used a fake $100 & $10 at Health Park, and another $100 at the Doctor's Way campus.

The incidents took place sometime between July 22-25, August 1st and August 9th.

"Some of the workers had noticed some of the bills looked a little different than ones in the drawer. We did contact law enforcement," said Welsch.

Secret Service agents say they are actively investigating the cases and have linked them to other counterfeit cases throughout Lee County. Authorities claim to also know the group that is passing the 'funny money' around.

Authorities say the fake cash was printed on bleached $1 and $5 bills, a common practice in counterfeiting.

Secret Service agents report around $5,000-$6.000 in counterfeit cash is successfully transferred in Lee County every 5 business days.