It is thought the Loftus Road club will meet with Barton in the next 24 hours to sort out his future.
The development comes after the 29-year-old to confirm he wants to join the Ligue 1 side, while also complain at his treatment by QPR.
His relationship with the club has rapidly deteriorated following his behaviour on the final day of last season against Manchester City, with the temperamental midfielder currently serving a 12-match ban for violent conduct.
Rangers stripped Barton of the captain's armband as a result of the incident and did not award him a squad number for the new season.
He has three years remaining on his contract in West London but if he is granted a free transfer he could be on his way to Marseille before the window closes on Friday, having been heavily linked with the French side.