The Rossoneri were already looking to sign a centre-back this month, but their search has been intensified following Tomori picking up a knee injury.
A number of loan options have been looked at, but AC Milan are not convinced and they are set to try for a top quality defender, with two players targeted by Newcastle those they are chasing, according to Italian outlet Calciomercato.com.
The Italians have already opened talks with Torino about Gleison Bremer, a player Newcastle have also been linked with as they search for centre-backs.
Newcastle have failed with two bids for the Dutchman amid Lille not wanting to sell this month, but AC Milan will try once again to change the French club’s mind.
The Serie A heavyweights want Botman to arrive at the San Siro immediately if they can convince Lille to let him go.
AC Milan currently sit second in the Serie A table, a point behind rivals Inter, and want to keep their title push on course.