Mills met with Forest manager Dougie Freedman for talks on Tuesday, according to the Nottingham Post, but the 28-year-old is yet to make a decision on his future.
The emergence of Leeds as a potential suitor may still scupper Forest's hopes of bringing the former Doncaster, Reading and Leicester player to the City Ground.
A two-year contract believed to be worth £10k-a-week from Forest is reportedly on the table for Mills, but he may now wish to consider the other options that are available to him.
Fulham are also potentially interested in securing his signature should he wish to move south, with Mills' leadership qualities viewed as being a vital commodity in the Championship next season.
But Mills has worked under Freedman whilst at the Macron Stadium, and left the Trotters at the end of the season after they cash strapped club were unable to offer the club captain a new deal.