The Mirror says Diarra's contract expired in the summer, but he has been training at Motspur Park in a bid to prove his fitness to Fulham manager Martin Jol.
And the Whites are weighing up whether to offer an appearance-based deal to the former Real Madrid star.
"I don't think he will ever be the player he was when he started at Lyon," said Jol. "That was 100 per cent. I felt he wasn't 100 per cent before but he was so influential with his passing and in the dressing room.
"We told him play three matches and then we will make an assessment.
"There are different scenarios like getting players and pay them when they play.
"But first we need clearance from the medical staff and his surgeon in Madrid to say he is fit."
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