Celtic fear leading clubs have made contact with Kristoffer Ajer as they look to sign him in the January window, Football Insider understands.

The Hoops have been trying to tie the centre-back, 21, down to a new deal after recently agreeing new contracts with Callum McGregor, James Forrest and Scott Bain.

A Celtic source has told Football Insider that the club are in talks with Ajer and are offering him around £25,000-a-week to bring his pay in line with their leading first teamers.

There are fears that Ajer has been “tapped up” amid links with top teams in the Premier League and across Europe, with Leicester City said to be in the hunt this week.

The giant centre-back has developed an impressive centre-back partnership with £7million summer signing Christopher Julien that was once again evident in last night’s 3-1 Europa League win over Rennes at Parkhead.

Ajer has come on leaps and bounds since signing for Celtic in January 2016 and has provided excellent value for his £550,000 transfer fee.

He has already clocked up a mammoth 27 appearances for Celtic this season, even filling in at right-back earlier in the campaign before three new arrivals in that position.

Ajer signed a new four-year deal in May of last year that runs until the summer of 2022, but Hoops chiefs recognise he needs to be rewarded with a new deal amid growing interest from elsewhere.

The 14-times Norway international has made 107 appearances in total for Celtic across all competitions.

In other Celtic news, it can be REVEALED that Kolo Toure has urged Brendan Rodgers to sign Hoops rookie who’s ‘blown him away’.