Casadei is a top young talent at Inter and Chelsea are interested in snaring away from the San Siro this summer.
The Blues have been in talks with his representatives over a potential deal and even approached Inter to negotiate an agreement.
Inter remain reluctant to lose the youngster and it has been claimed that Chelsea’s first offer has been rejected by the Nerazzurri.
According to Italian daily Gazzetta dell Sport, Chelsea offered around €8m for the teenage midfielder but Inter were quick to reject the bid.
The Nerazzurri are open to letting the youngster go if a buy-back option is part of the agreement.
They want to avoid what happened with Nicolo Zaniolo, who left Inter for Roma and is now one of the best young talents in Italy.
Chelsea are not interested in doing such a deal as they see Casadei as someone who could be a big part of their future.
The Blues would have to double their initial bid to convince Inter into selling Casadei this summer.
The youngster has suitors in Italy as well such as Torino, Sampdoria and Sassuolo, who are ready to include the buy-back clause that Inter want.