Blues midfielder Bacuna alerted fourth official Tom Nield to the incident in the closing stages of his side’s 1-0 Sky Bet Championship defeat on Saturday.

West Midlands Police confirmed the arrest of a 50-year-old man from Dudley, who has since been released on bail, and appealed for witnesses.

West Brom said in a statement: “West Bromwich Albion has suspended the season ticket of a man arrested on suspicion of racially abusing Birmingham City player Juninho Bacuna at The Hawthorns on Saturday.

“A 50-year-old from Dudley has been detained and questioned on suspicion of a racially aggravated public order offence.”

The Baggies added: “The club continues to offer its full support to West Midlands Police’s criminal investigation of this matter and remains in contact with Birmingham City to ensure Juninho Bacuna receives the support he requires.”

They warned that anyone who is found guilty of racially abusing their players could face a lifetime ban, saying: “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.

“Albion will continue to work with the Football Association, the EFL and all relevant authorities to rid the game of racism.”

West Midlands Police said that the man had “been bailed with strict conditions — which includes not being able to attend any football game in the UK — while our enquiries continue.

“We remain keen to hear from anyone who was in the Halfords Lane stand — who saw or heard anything towards the end of the second half — to come forward as it could help our investigation.”