While the Norway international is a key man at the Glasgow giants, there is an acknowledgement that the centre-back will eventually move to a bigger club.
According to Calciomercato, this has resulted in Celtic setting an asking price of £18m ahead of the next transfer window.
Although Neil Lennon would prefer not to sell Ajer, at least one big-money departure may be required in order to fund moves for other players.
Since costing just £500,000 in July 2016, Ajer has made 129 appearances in all competitions. body check tags ::