Southampton said they are "disgusted and disappointed" after defender Kyle Walker-Peters suffered racist abuse online on Sunday.
Offensive remarks were posted in the comments of the 25-year-old's week-old Instagram post after his side's goalless draw with Manchester United.
The club have forwarded the messages concerned to Hampshire Police.
Southampton also contacted police in February 2021 after midfielder Alex Jankewitz was racially abused online.
In a statement, the club expressed their annoyance at social media platforms' inability to resolve the problem.
It said: "More than two years on, we find ourselves in the exact same position: disgusted and disappointed in the behaviour of those online who lower themselves to abusing players for the colour of their skin.
"What is equally frustrating is the lack of meaningful action in those two years from the social media platforms who allow such hatred to breed and fester."
A racist term was directed at full-back Walker-Peters in response to a comment about United substitute Alejandro Garnacho.
Winger Garnacho appeared to be in pain after a challenge by Walker-Peters in the closing stages of the game at Old Trafford.
Two years ago, Swiss Jankewitz, now 21, was the victim of racist abuse after being sent off during Saints' 9-0 away defeat by United.
Southampton said the club "fights every day" to remove abusive people in order to protect staff and fans who "celebrate" diversity in football.
"We can only hope that they finally pay attention to what continues to be a major problem and that we do not find ourselves repeating these words in another two years' time," the statement added.
