Newcastle have alerted police after Nigerian striker Sammy Ameobi was subjected to racist abuse on Twitter, the Premier League club confirmed on Tuesday.
"Newcastle United are aware of a racist remark that was directed towards Sammy Ameobi via Twitter on Sunday evening," the club said.
"The club and Sammy have reported the matter to the police, who are now dealing with the incident.
"The racist comment is wholly unacceptable. Newcastle United will not tolerate racism of any kind and will take the strongest possible action against those responsible."
The Twitter account which posted the slur against Ameobi, the 19-year-old younger brother of Newcastle forward Shola Ameobi, has since been closed.
Ameobi made an appearance as a substitute in Monday's 3-1 victory over Stoke which saw the Magpies climb to third place in the standings.