Strathclyde Police have confirmed they are investigating claims by Rangers that two of their players were racially abused.
It is understood the Ibrox pair allegedly received the abuse via their Twitter accounts overnight.
Neither player has been named by police or the club.
However, Kyle Bartley - who spent last season on loan at Rangers from Arsenal - has indicated on his own Twitter page that the players targeted were Sone Aluko and Maurice Edu.
Rangers tweeted from their official account: "The Club has this morning been made aware of racial abuse directed at two of our players.
"We have reported this matter to the Police who are now investigating the matter."
A Strathclyde Police spokesperson said: "We can confirm the matter has been reported to us and we are investigating."
PFA Scotland head of communications Jack Ross said: "We are appalled when any of our member players are targeted in any discriminatory manner.
"Following the new anti-discrimination legislation brought in by the Scottish Government we look forward to the police investigating fully and taking appropriate action."
Speaking as a FIFPro Europe board member, Tony Higgins, who is also president of PFA Scotland, said: "On the back of the recent Panorama programme, it is imperative that not only football but police authorities act quickly in these matters.
"Racism has no place in a civilised society."