The 29-year-old has been linked with a move away from Loftus Road in the fall-out from last season's meltdown against Manchester City.
Barton received a 12-match ban after being sent off at the Etihad Stadium, a sanction which looks likely to be enforced by Ligue 1.
"Joey wants to play in Marseille this season," Willie McKay, Barton's agent, told French radio station RMC. "We are negotiating, but nothing is done for now.
"I don't want to comment more with respect for [general manager] Jose Anigo and the president Vincent Labrune."
Barton joined QPR on a free transfer last summer.