West Ham United are allegedly demanding the return of a £1m loyalty bonus from Dimitri Payet after agreeing to sell the player to Ligue 1 side Marseille.
The Frenchman is poised to return to his homeland after the two clubs settled on an initial fee of £25m.
Payet's camp insists that his West Ham exit is not financially motivated and the Hammers want him to prove such claims by returning the bonus he was given in September, according to The Mirror.
The playmaker, who signed a new five-year deal worth £120,000 last February, was handed the bonus in an appeasement attempt after returning from the European Championships unsettled.
However, his recent transfer spat saw him refuse to train with or play for West Ham again.
Marseille's fee could eventually rise to £30m subject to specific conditions being met.