Gray has already been charged with misconduct by the Football Association as a result of allegedly homophobic and distasteful tweets posted between January 9 and March 11 2012.
The FA has confirmed to Press Association Sport it is aware of reports of an additional comment made by Gray on social media in July 2014
According to the Observer, Gray began the tweet: "I hate lightys!"
'Lightys' is a reference to people of mixed race and is widely considered a derogatory term.
The 25-year-old Gray has deleted his Twitter account.
He has until 6pm on Wednesday to respond to his FA charge, which could lead to a fine or lengthy suspension.
Gray's early 2012 tweets were shared widely last weekend after he scored his first Premier League goal against Liverpool.
In one tweet, Gray wrote: "Is it me or are there gays everywhere? #Burn #Die #Makesmesick"
He later issued an apology in which he admitted he had made mistakes in the past.
He said: "I have a lot of regrets regarding a number of things I've done in the past and realise I have made some big mistakes, none more so than these tweets, but I would like to stress that I've worked incredibly hard to completely transform my life since that time.
"To clarify, I do not hold the beliefs written in those tweets whatsoever
I can assure everybody that I am absolutely not homophobic and as said previously I can only apologise and ask for forgiveness to anyone I offended."
Source : PA