The Scandinavian is expected to bring his five years at Parkhead to an end this summer with Norwich City front-runners for his signature, though Newcastle and previously AC Milan have been linked with a move for the 23-year-old.
Ajer’s departure would leave Celtic very short at the back after loan disappointment Shane Duffy headed back to Brighton earlier this year leaving Nir Bitton, Stephen Welsh and crocked Christopher Jullien as the basis for the centre-backs.
That would intensify the need for replacements and the club is believed to be in talks with Rubin Kazan over Swedish international Carl Starfelt becoming Ange Postecoglou’s second summer signing.
The manager has already inherited new recruit Liam Shaw from Sheffield Wednesday and fellow Owl Osaze Urhoghide became the first transfer of the Australian’s era last week.
The club is currently in Newport for pre-season training and face the Hillsborough club on Wednesday.