Referees' body PGMOL says it is taking new allegations around Premier League official David Coote "very seriously".
Coote is suspended from his role pending an investigation into a video which emerged earlier this week, in which the 42-year-old appeared to make disparaging remarks about former Liverpool manager Jurgen Klopp.
On Wednesday the Sun newspaper published pictures it says were taken during this summer's European Championship, alleging they appear to show Coote sniffing a white powder through a rolled up US bank note.
Coote was working at the Euros in his capacity as a match official.