The Black Cats have parted ways with the centre-back, who moved to the club for £8 million in 2016.
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The Tunisia international appears primed to join Les Verts on a four-year deal.
Arsenal look set to beat Manchester United and a number of top clubs from Europe to the signing of highly-rated Sunderland teenager Sam Greenwood.
Sunderland have sacked manager Chris Coleman after failing to keep the club in the Championship.
Fulham came from behind to secure a 2-1 home victory over relegated Sunderland and move up to second place in the Championship.
Wolves secured the Championship title with a 4-0 victory over Bolton at the Macron Stadium on a day when Sunderland were relegated.
Club officials reported to be concerned that Newcastle fans will attend their remaining home games to cheer on their opponents.
Veteran Sunderland defender John O'Shea has insisted he has no plans to retire just yet despite his 37th birthday fast approaching.
Ex-Sunderland chairman Niall Quinn dismissed reports he is part of a consortium considering a takeover of the struggling Championship club.
Sunderland have suspended midfielder Darron Gibson with immediate effect after he was charged with driving with excess alcohol.