The Football Association says it is investigating an allegation that referee David Coote discussed giving a yellow card with a fan before a Championship match.
Coote, 42, says he denies the new claims and calls them "false and defamatory allegations".
The referee is already under investigation by the FA and has been suspended by refereeing body the Professional Game Match Officials Limited (PGMOL) and European football's governing body Uefa following separate allegations about his conduct.
A new report in the Sun newspaper on Tuesday claimed Coote exchanged messages with a fan discussing giving a yellow card before and after a game between Leeds and West Brom in 2019.