The midfielder will miss the club's Coupe de France tie against PSG after club chairman Olivier Sadran punished the 23-year-old, whose contract is set to expire in the summer.
Toulouse coach Alain Casanova has backed his chairman's decision, although he conceded his absence will be a loss to the side.
"The whole club shows full solidarity to that chairman's decision," he told L'Equipe. "It is really a shame a player educated at the club could leave as free agent. His absence is big loss for the team, but that decision is logical."
Sissoko has been a regular in the Toulouse side in recent seasons, and has made five appearances for France.
Newcastle has tied up deals for Massadio Haidara and Mapou Yanga-Mbiwa in recent days, and is set to seal a move for Yoann Gouffran soon after the player revealed on Twitter that he would be joining the Premier League side.