Forest have said they want at least £10million for the 20-year-old however, despite him having played only eight times in the Championship, says Sky Sports.
The Bees are not prepared to pay that much for a player who was on loan in League One for most of last season, where he helped Lincoln City reach the play-off final.
Brentford are considering making a bid for the Wales international, who scored 11 goals for the Imps and started Forest's first three games of this season, before the deadline but also have other options for a new attacking-midfielder.
The newly-promoted Premier League side also want to strengthen at right-back before the deadline but have moved on from Hamburg's Josha Vagnoman.
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