British police are investigating death threats made to Ireland's Stephen Hunt and his Reading team-mate Ibrahima Sonko in the wake of their side's recent Premiership game with Chelsea.
The pair were involved in the incidents which saw Chelsea goalkeepers Petr Cech and Carlo Cudicini hospitalised during the Royals' 1-0 Madejski Stadium defeat last month.
Thames Valley Police said: "The club is helping us with our inquiry and the matter is being investigated."
A Chelsea spokesman added: "There is nothing to suggest these threats came from genuine Chelsea fans."
The first letter was treated as a joke and pinned up on the door of Reading's training ground dressing room, but the arrival of subsequent letters saw the police called in to investigate.
Rep of Ireland B international Hunt was involved in a first-minute collision with Cech, who suffered a fractured skull which is expected to keep him out for the rest of the season.
"The club is dealing with all my letters and I don't want to say any more," said the Waterford man.
Cudicini was carried off on a stretcher following a final-minute collision with Sonko and required oxygen. He only recently returned to action, while Cech is still out.
Sonko confirmed he had received a letter but made no further comment.
Neither player faced any sanction from the Football Association.
Chelsea's spokesman added: "Naturally, we condemn any threats of this nature and we will assist the police fully if - and we stress if - there is any evidence linking theses threats to any of our supporters."
Reading manager Steve Coppell said: "We went through the proper channels and we reported it. Obviously it was the work of a nut but nuts can be dangerous.
"It is not a worry though. I don't think it will affect the players because we actually had one of the letters on the noticeboard for a week or so to show just how stupid and futile something like that is.
"But at the same time, at the back of your mind, we thought we had to report it.
"I wouldn't have thought this is a unique situation. There is so much at stake and football has been likened many times to a new religion so you are going to get extremists who are going to take it too far."