St Mirren have vowed to ban for life fans who allegedly threw coins and spat at an unconscious Dundee United supporter during their William Hill Scottish Cup defeat.
Buddies chiefs have hit out at the "completely and utterly unacceptable" behaviour of a small group of fans on Saturday.
The United supporter was injured while celebrating one of the Ladbrokes Championship outfit's goals during their 2-1 win in Paisley.
But in a statement posted on the Saints website, club officials claim he was targeted by a section of the home support as he was being led away for treatment.
"On Saturday a Dundee Utd supporter suffered a serious head injury after the away crowd surged forward after United's first goal," the statement said. "This is something we have warned our own support against on numerous occasions so hopefully this will make people realise how dangerous this can be.
"Given the seriousness of the injury the decision was taken to remove the fan by the quickest means possible which was through the vomitory at W7.
"While the unconscious supporter was being removed there were numerous people standing above the vomitory who decided to spit and throw coins at him.
"This is completely and utterly unacceptable. We cannot allow the actions of a very small number of fans to ruin the reputation of St Mirren Football Club.
"Some of the people responsible were identified but unfortunately the quality of the CCTV footage of the incident is such that at this time we are unable to pursue this to the degree of certainty that would allow prosecution.
"If we are able to clearly identify the culprits, regardless of what happens in a legal sense, they will be given a lifetime ban from our stadium.
"We would ask anyone with any information or footage of the incident to contact the club on email@example.com.
"Any information provided will be treated in the strictest confidence.
"For the avoidance of any doubt antisocial behaviour will not be tolerated in ANY area of our stadium."
A spokeswoman for Police Scotland said: "We were contacted by the club about an incident and enquiries are ongoing."