Blues defenders Antonio Rudiger, Andreas Christensen and Cesar Azpilicueta are all out of contract at the end of June, with negotiations over extensions so far proving unsuccessful.
Chelsea came close to luring Kounde from Sevilla last summer, only to balk at Spanish club's £60million asking price.
The 23-year-old admitted missing out on a move to the Premier League side unsettled him at the start of the season.
And transfer expert Fabrizio Romano tweeted: "Chelsea have Jules Kounde as top target in their summer list, as reported days ago."
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