Ajer joined Celtic in the summer of 2016 and has so far made over 150 appearances for the Hoops in all competitions, however he is edging towards the exit door.
While the season gone by was a disappointing one for the Hoops as they finished runners-up to Rangers in the Scottish Premiership, Ajer’s performances were impressive enough to have clubs around Europe take notice of him.
He made 31 appearances in the league for the Hoops in the recently concluded campaign and the young defender could be set to leave Celtic Park this summer.
Newcastle United want to sign Ajer and a £6m fee to take the Norway international to St James’ Park has been mooted.
However, Leverkusen have now made contact with Ajer’s representatives to register their interest as they explore taking him to Germany.
The German side did business with Celtic in January when they snapped up Jeremie Frimpong for £11.5m.
Ajer has one year remaining on his current contract with the Hoops and could be sold by the club this summer.