Leeds Rhinos confirmed they are investigating reports one of their international stars posted sick jokes about the Japanese earthquake and tsunami on the web.
The Rhinos launched an inquiry after prop forward Ryan Bailey, 27, allegedly made the remarks on Facebook.
They have now been taken down.
A Rhinos spokesman said: “We are taking the allegations very seriously.”
He said an internal disciplinary inquiry was under way.
Bailey has played for the Rhinos all his career and has made more than 200 appearances for the club since his debut in 2002, though he has yet to feature this season because of injury.
He has been capped four times for Great Britain and four times for England.