Katic is currently signed with Croatian club Slaven Belupo, who are expecting offers for their defender around the £2million mark. The former U21 Croatia international earnt his first senior cap in May last year.
The 21-year-old's agent, Mladen Kliskinic, is reportedly travelling to Russia on Tuesday in order to begin negotiations with Spartak, but Rangers are keen to hijack the deal to sign Katic themselves.
A spokesperson for Kliskinic told 'Sportsmail': ''There was a representative from Glasgow Rangers in Croatia three weeks ago. There is another story that Spartak Moscow are also interested.''
''Mladen Kliskinic has booked a flight to go and speak to them on Tuesday but we are waiting for Slaven Belupo to confirm they've accepted a concrete offer. Until that happens nothing can be finalised.''