The U.S. Secret Service is warning Long Island residents about a batch of counterfeit $100 bills currently in circulation up and down the East Coast.

They can be identified by the number 77 on the back image. Officials say the number may also appear toward the end of the serial number found on the face of the bill.

On its website, the Secret Service lists several ways to identify legitimate cash. It says authentic bills should have a vertical security thread that spells out the amount. The money should also contain red and green fibers embedded in the paper and a watermark that replicates the face on the bill.

Authorities are urging the public to contact police if they come into contact with any counterfeit money.

Officials say counterfeit money deposited in a bank account will be seized without reimbursement.

Nassau Police Detective Richard Harasym told News 12 that the police department is working closely with the Secret Service in its investigation into the origin of the fake money.