The 29-year-old's future with QPR has been the subject of much debate this summer after he was stripped of the captaincy and given a 12-match FA ban.
Barton spent pre-season training with Fleetwood, but would not be able to join npower League Two newboys on loan as it is understood the Football League would refuse to register him while his ban remains.
However, the fact he was not given a squad number by QPR may suggest he has no future with the club.
The Ligue 1 club have yet to table an offer, though, and are thought to be the only club to have expressed an interest in the former Newcastle man.
His old number 17 shirt was given to summer signing Ryan Nelsen.