Charlie Austin has been asked by the Football Association to explain his offensive comments aimed at Southampton fans on social media, the PA news agency understands.
The West Brom striker, who joined the club from Southampton last summer, responded to criticism from Saints fans on Twitter with an expletive-laden rant on Saturday.
Austin, 30, had initially retweeted a comment on the dangers of social media, but responded to replies from two Southampton fans by mocking their club's supporters in general.
The expletive-laden tweets have since been deleted from Austin's Twitter account.
The FA is understood to be investigating the incident and has asked Austin for his observations.
In January 2019, Austin admitted to an FA charge and was banned for two games after gesturing at Manchester City fans when substituted in Southampton's 3-1 defeat at St Mary's on December 30.
Austin made over 80 appearances for Southampton, scoring 20 goals in all competitions, during a two-year spell at the club before signing for West Brom for a reported £4million in August 2019.
He has scored nine goals in 28 appearances in total this season for West Brom, who are top of the Sky Bet Championship.
