The incident happened at St Andrew’s during the Blues’ Championship match against Hull City on Wednesday.
This comes after Birmingham midfielder Juninho Bacuna reported being racially abused during his side’s 4-1 win over Huddersfield Town earlier this month.
Police have taken a 52-year-old man in custody on suspension of a racially aggravated public order offence at St Andrew’s.
They have also arrested another man in his 20s for allegedly assaulting a steward.
Hull were on a four-game winless run but they bounced back with an impressive 2-0 victory thanks to goals in either half from Liam Delap and Jaden Philogene.
The Blues sacked John Eustace as manager earlier this month, installing Wayne Rooney in his place.
But the 38-year-old has made a terrible start as the team has lost the first two matches of his reign.
The former DC United boss will likely find things more difficult in the coming weeks, with Southampton and Ipswich Town next on their fixture list.
Birmingham were sixth in the Championship standings at the time of Eustace’s departure, but they have now slipped to 12th in the table.
- Manchester City back on track after 2-1 victory over Luton Town
- Aston Villa 1-0 Arsenal: Bailey goal extends Villains’ unbeaten home run
- Pep Guardiola denies City are reliant on Rodri but the stats disagree
- Preview: Aston Villa vs Arsenal – prediction, team news, line-ups
- Man Utd boss Ten Hag scoops Premier League MOTM award
- This Week In Football: Last-minute UWNL drama, Santos relegated & more
- Morning Mix: Arsenal face acid test at Villa, Chelsea boss has no excuses
- Arsenal or Liverpool: Who is better placed to beat Man City to the title?
- Copa America 2024 draw: Argentina to face Chile, Brazil and USMNT discover their groups
- Four reasons PSV Eindhoven are overtaking Ajax on and off the pitch