Sinclair, who has recently worked as a pundit for talkSPORT, responded to the news by tweeting: 'Racism was outlawed in England in the 60’s & its been allowed to thrive so why should black & brown mourn!! #queen'
The tweet was later deleted, with Sinclair's Twitter account also disappearing in the hours that followed.
In a statement on Friday, the station confirmed that the ex-footballer would be investigated following his tweet.
TalkSPORT said: "Trevor Sinclair will not be on air while we carry out a thorough investigation into the circumstances and timing of his tweet.