Featherstone have suspended former England forward Darrell Griffin and not allocated him a squad number for the new season.
Griffin, 36, has spent the past two seasons with Rovers having previously played for Wakefield, Huddersfield, Leeds and Salford in Super League.
A club statement said: “Featherstone Rovers can confirm front-row forward Darrell Griffin has been suspended pending an internal investigation.
“The club will be making no further comment at this time.”
Griffin’s name was absent from the 2018 squad numbers issued by Featherstone following their squad launch night on Friday.
However, the number 15 shirt remains vacant.