Lancashire police have launched a criminal investigation into Birmingham striker Dwight Yorke's claim he was racially abused at Blackburn. Police heard reports from Blackburn safety officers on Monday and studied CCTV and video footage of the incident.
The Football Association has launched its own inquiry into Yorke's allegations he was abused by two home fans as he warmed up on the touchline.
Both clubs are also to conduct their own investigations into the claims.
A Blackburn statement read: "We will give the Police - who now intend to interview all relevant parties - our full co-operation during the length of that investigation.
"We would like to stress that this was an isolated incident and that we deeply regret any embarrassment caused to Dwight Yorke and Birmingham City Football Club.
"We want to be quite clear that racism will not be tolerated at Ewood Park."
The Football Association and the Premier League issued a joint statement about the incident at Blackburn.
The statement read: "The FA and the Premier League welcome the swift action taken by Blackburn Rovers in launching an investigation.
"We fully support Blackburn Rovers' entirely appropriate reaction to this incident and their involvement of the Lancashire Police who will ensure that this matter is dealt with as the law demands.
"The FA, the Premier League and The Football League condemn racism in all its forms and are committed to stamping out any form of racist behaviour from football.
"This isolated incident is a reminder of the need for continued vigilance."
Blackburn have confirmed one fan had been ejected for making a gesture at Yorke.
Yorke's claims come just four days after racism made an unwelcome return to the spotlight when England players were abused during a friendly in Spain.
Birmingham boss Steve Bruce said: "They racially abused him. Dwight is bitterly upset and angry.
"Apparently it is monkey taunts and that is sick. It's all right him getting a bit of stick but when it comes to what we've just seen in midweek, everybody is sickened by it."
Yorke left Rovers for St Andrew's in August, bringing to an end a tempestuous two-year association with the club.
The Trinidad international was roundly booed by fans as he warmed up and in particular when he replaced Darren Anderton as substitute.
Blackburn chief executive John Williams said: "We want to talk to the police, we want to talk to our stewards, we want to review all the CCTV footage.
"We'll be very disappointed if it shows that there's been any evidence of racism, but if there has, we'll take the strongest possible action.
"This is not something that we want to tolerate at Ewood Park."
Birmingham managing director Karren Brady also stressed the importance of "stamping out" racism in English football.
"It was a very small minority but it is incredibly upsetting for a player and something needs to be done about it," Brady told BBC Sport.
"John Williams is a very good chief executive and will leave no stone unturned in finding out what happened."
However, Birmingham chairman David Sullivan played down the incident.
"It's been blown out of all proportion - I heard absolutely nothing.
"If it's three out of 22,000 who make racist comments then it's not very nice.
"You have to pick up on it and ban those people from the ground but I just can't believe that it's that big a deal."