London Irish have reported a "racially abusive and threatening message" sent to Fijian forward Albert Tuisue to Instagram and the police.
Irish said Tuisue received the message on his Instagram account following their 52-27 Gallagher Premiership defeat at Newcastle on Saturday.
"As a club, we understand criticism after a defeat or poor performance," said a statement posted on the official Irish website.
"But when that criticism becomes racially abusive and threatening – and especially when it becomes personal – we will protect our players and staff from being subjected to such treatment from members of the public.
"We have reported the message to Instagram and also to the police, as we will do for any abuse of this nature.
"As a club, we would like to thank the police and the cyber-crime unit for following up and dealing with this issue in such a prompt and speedy manner.
"The fact that this happened just a week after a period where clubs, players and stakeholders across various professional sports came together for a boycott of social media for this very reason, again shows just how much work still needs to be done to step up and stand against hate speech and abuse on these platforms."
Irish have pledged to continue the fight for change, working with Premiership Rugby and supporting BT's 'Draw The Line' campaign to combat hate speech and abuse on social media.
The club added: "We urge social media companies to take strong action and implement real change on their platforms, which will enable its users – our players, staff or anyone who is on these platforms – to open their accounts and not have to worry about what they might find.
"We have chosen to make this public statement so people will understand that London Irish will defend its players and staff from this type of abuse.
"Albert has the full and unwavering support of everyone at London Irish, as well as Premiership Rugby, and the message remains clear: it's time to 'Draw The Line.'"
Responding to messages of support on Twitter, Tuisue, 27, wrote: "Thank you for your support. God bless."