Castagne has been linked with a Celtic move for quite some time.
Sky Italy journalist Gianluca Di Marzio has claimed on his website that Celtic tabled an offer worth £8.8million to sign Atalanta right-back Timothy Castagne in the January transfer window.
Celtic have been after a right-back for quite some time and it is believed 23-year-old Castagne was a top target for Celtic and Brendan Rodgers, with both Mikael Lustig and Cristian Gamboa's contracts expiring this summer.
A two-time Belgium international, Castagne was pinpointed as Lustig's long-term replacement as he continues to shine from the right side of defence in Serie A, after joining the club from KRC Genk in the summer of 2017.
This season, he has been in the form of his life. During 20 league and cup appearances, Castagne has found the back of the net three times and created three more goals in assists - as well as helping his side keep nine clean sheets.
Di Marzio claims Atalanta have decided to place their faith in star players such as Castagne rather than selling, with the club also rejecting West Ham's £35million bid for Duvan Zapata and AS Roma's bid for Josip Ilicic.
It meant that despite Celtic's sizeable offer for Castagne, they had little chance of luring the Belgian to Parkhead. Instead, the Hoops have signed Jeremy Toljan on loan from Borussia Dortmund, with a view to a permanent deal.