Celtic have been hit by the bombshell Kristoffer Ajer wants to quit this summer after he knocked back their offer of a new £25,000-a-week contract, Football Insider understands.

The Norwegian defender’s agent has gone public with the player’s intention of leaving at the end of the season.

A Celtic source has told Football Insider that the club started trying to tie Ajer, 21, down to a new contract before Christmas and made multiple offers of up to £25,000-a-week.

But hopes of a breakthrough evaporated and the Hoops now face an uphill battle to stop the giant centre-back from leaving.

Celtic have long been aware of interest in Ajer from leading European clubs, with Serie A giants AC Milan among those linked.

He has developed impressively over the last 18 months and is firmly established as a first choice in Neil Lennon’s all-conquering team.

Ajer’s agent Tore Pederson has suggested it’s inevitable Ajer will leave Glasgow at the end of the season.

“He will not extend his contract with Celtic and will leave this summer,” Pedersen said. “There are several clubs who are interested, but I can’t go into their names. There are many who have followed him for a long period.”

Ajer has already clocked up a mammoth 49 appearances for Celtic this season, including with great success in the three-man defence used regularly of late.

Since signing for Celtic in January 2016, the Norway international has made 129 appearances for the club and provided excellent value for the £550,000 transfer fee.

Ajer signed a new four-year deal in May 2018 that runs until the summer of 2022.

In other Celtic news, it can be REVEALED that big-money 2019 signing is set for crunch talks about QUITTING the club.