L'Equipe state now state Soppy's role as understudy will be taken up by Lorenz Assignon for the Ligue 1 side moving forward.
The 19-year-old appears a perfect fit for Ange Postecoglou 's attack-minded formation and he is understood to be available for around £4.3m with only one year remaining on his current deal.
Soppy has been capped by France up to Under-18 level and he will see Celtic have a proven track record of developing French players such as Moussa Dembele and Odsonne Edouard.
Celtic have been linked with a clutch of central defenders in Carl Starfelt, Cameron Carter-Vickers, Ben Davies and Mario Vuskovic but Soppy is very much an attacking full-back.
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