The forward is said to have been the subject of an abusive internet campaign on the social networking site, a claim Northumbria police are now looking into.
The allegation is yet another in a long line of incidents regarding racial abuse to hit English football this season alone.
Liverpool's Luis Suarez is set to return from his eight-match ban for racially abusing Patrice Evra in the club's next fixture and Chelsea captain John Terry appeared in court this week over his alleged abuse of QPR defender Anton Ferdinand.
Magpies officials confirmed in a statement that they were fully co-operating with authorities on the matter.
"We have liaised with Northumbria Police and the matter is now in their hands," a spokesman said.
"We have a zero-tolerance approach to racism and will always seek to take the strongest possible action."
Northumbria Police also insisted that the remarks are being taken very seriously.
"We have received a report of racist comments made on Facebook, on which we're working closely with Newcastle United," a police spokesman said.
"Northumbria Police take all reports of racist abuse very seriously and inquiries are being conducted."