United fans have been urged to come forward with information regarding a second coin-throwing incident in as many months.
The latest incident occurred just after the third United penalty in the JPT tie against Notts County on Tuesday night and closely follows a similar event during the league clash with Colchester United.
In both incidents, a coin was thrown in the direction of the opposition goalkeeper.
The Club can confirm South Yorkshire Police are investigating the incidents and have also pleaded for Blades fans to come forward with any information.
United managing director Mal Brannigan said: "Behaviour of this manner will not be tolerated and anyone found to have committed this offence will receive an automatic life ban from Bramall Lane. This sanction will be separate to any action South Yorkshire Police can impose.
"We are working closely with South Yorkshire Police to identify the individual or individuals who committed these mindless acts. The Club has, in the past 12 months, installed and upgraded its CCTV network throughout Bramall Lane and in particular The Kennedy Kop Stand. The footage that comes from the cameras is very clear and was used to ban two individuals following unwanted behaviour last season.
"Bramall Lane has a very good reputation for being a safe environment to both watch and play football. The Club will do its utmost to ensure this remains so."
Anyone with information should contact firstname.lastname@example.org