West Ham United have confirmed the Football Association is investigating a comment made by Ravel Morrison on Twitter.
Morrison, 19, is reported to have made a homophobic comment - which has since been deleted - in response to another Twitter user.
The midfielder wrote: "Crack head ? Go suck out u little f****t your a guy that talks if u see me you try slap me I'm in manchester every week."
A statement on the club's official website read: "West Ham United are aware that the FA have written to Ravel Morrison asking for his observations regarding comments on Twitter.
"Ravel and the club will co-operate fully with the FA's request and have until Monday evening to respond. There will be no further comment from West Ham United or Ravel at this stage."
In response to the story, a spokesman for the Justin Campaign, which aims to tackle homophobia in football, was reported as saying: "It's disappointing to hear that yet another professional footballer in England has used homophobic language."
Morrison joined West Ham United in January after failing to agree a new deal with Manchester United, where his potential was highly-regarded although question marks remained over his temperament.