Birmingham boss Tony Mowbray has called for harder punishments for racist abuse after Juninho Bacuna reported being taunted at The Hawthorns.
Blues winger Bacuna reported the alleged racism to referee David Webb, having identified abuse aimed at him by a fan during their derby at West Brom.
It is the second time Bacuna has reported such an incident this season.
"The consequences for racially abusing footballers have got to be stronger," Mowbray told BBC Radio WM.
"I'm not sure if they have yet identified the individual but Bacuna recognised him and pointed him out. And he was rightly upset about it. Obviously it's not acceptable.
"It's not the first time these things have been said. Not just this club, and not just Bacuna. It's a beautiful game and we just don't want it.
"The stupid idiots have got to be made to think about the consequences for doing these things."
After their 1-0 Championship win on Saturday, West Brom said they would "offer full support to West Midlands Police in their criminal investigation".
The statement added: "The club takes a strong stance against all forms of discrimination and will do all it can to ensure anyone found guilty of racism faces the toughest available legal punishment, in addition to a lifetime ban from The Hawthorns."
Birmingham, meanwhile, thanked stewards, security and the executive team at The Hawthorns for "acting immediately" after Bacuna's complaint.
"The football club offers its full and unwavering support to Juninho," they added.
Bugiel reports alleged racist abuse at Bradford City v AFC Wimbledon
There was also an incident at the end of AFC Wimbledon's 0-0 draw at Bradford City.
Play was briefly stopped in the League Two match after Wimbledon's Lebanon striker Omar Bugiel reported being the victim of alleged racist abuse from someone in the crowd at Valley Parade.
Speaking after the match, Wimbledon manager Johnnie Jackson said: "I think there was some racist abuse aimed towards Omar Bugiel. He's speaking to the referee to report it. I don't know what was said. Obviously, we'll wait to see the report until I comment further but someone in the crowd has said something to him that they shouldn't have done."
Writing on X, Wimbledon said: "We'd like to place on record our thanks to Bradford City for the way they responded to the incident that occurred towards the end of today's game. Racism has no place in football."
Bacuna was also subjected to racist social media abuse in October 2022, from accounts "based outside the UK", after going on international duty with Curacao to Indonesia.
That was condemned by Blues, as was the abuse he suffered on his own ground in September, after which Birmingham City owner Tom Wagner issued the threat of a lifetime ban.
That was the second time in a year that racial abuse at St Andrew's has been reported against a home player, after then Blues club captain Troy Deeney endured the same experience in February.
It is also the second time this week that Albion have found themselves under investigation following an incident in the same section of the Halfords Lane Stand.
They issued lifetime stadium ban threats to fans before Saturday's game, to eliminate any chance of a repeat of last Sunday's violence in the Black Country Derby against Wolves.
Last month, Coventry City midfielder Kasey Palmer reported being racially abused during a 2-1 Championship win over Sheffield Wednesday at Hillsborough.
Fifa president Gianni Infantino called for the implementation of an automatic forfeit of games for teams whose fans commit racist abuse.