Brentford also want to sign the Posh star, per Football Insider.
The source claims Dembele is seen by scouts as one of the brightest prospects in the Football League.
He was impressive for Peterborough in the second half of last season.
Dembele, 23, is a winger who can play on either flank, managing seven assists and four goals in eight games since the turn of the year.
The Ivorian has played a total of 77 games for the League One club, scoring 13 and getting 16 assists in those matches.