Olivier Ntcham has left Celtic at the end of his contract after a four-year spell at the Scottish Premiership club.
The French midfielder, who joined from Manchester City in 2017, won three consecutive league titles at Celtic Park, playing 150 games for the club.
Ntcham spent the second half of last season on loan at Marseille but had joined up on Celtic's pre-season training camp last month under new manager Ange Postecoglou.
In an Instagram post, accompanied by a picture of a late winner away to Lazio in the Europa League in November 2019, Ntcham wrote: "I would like to thank everyone at Celtic for the 3 years in half (sic) l was there.
"Thanks to all the coaching, the staff, the players and everyone working at the club.
"Finally, I would like to thank the loyal supporters who have always supported us.
"I wish you all the best for the future."
Ntcham first expressed his desire to leave Celtic in the summer of 2019 but after a potential move to Porto failed to materialise he was reintegrated into the squad under Neil Lennon.
A Celtic club statement added: "The club can confirm that Olivier Ntcham's contract with #CelticFC has come to an end.
"Everyone at the club wishes Oli nothing but success for the future."
Andre Villas-Boas, then manager at Marseille, offered his resignation over the signing of Ntcham - citing a disagreement over the Ligue 1 club's sporting policy following the transfer.
Marseille did not take up their option to buy Ntcham, who made just two starts in France, but he was at their friendly against Villarreal on Saturday while Celtic lost 2-1 at Hearts in their Scottish Premiership opener.