Rapper Mellow Rackz is in police crosshairs after cops say she received right into a battle along with her boyfriend’s ex-girlfriend and swiped the lady’s cellular phone.

Regulation enforcement sources inform TMZ … Mellow Rackz is a named suspect on a theft report after getting right into a battle within the foyer of a West Hollywood resort early Monday morning and allegedly strolling away with another person’s cellular phone.

We’re advised Mellow was on the town for Rolling Loud, and her boyfriend booked them a resort room … and likewise, unbeknownst to her, booked a room in the identical resort for his ex.

Our sources say Mellow ran into her man’s ex within the foyer and a battle broke out … with Mellow allegedly punching the lady within the face, leaving purple marks on her face.

We’re advised sooner or later through the altercation the lady dropped her telephone, and Mellow snatched it and left, telling the lady, “What are you going to do about it?!?”

Our sources say police have been known as to the resort and officers spoke to the alleged sufferer … however we’re advised Mellow refused to come back out of her room to talk with legislation enforcement, telling them by way of the door to speak to her lawyer.

We’re advised officers took a theft report and named Mellow Rackz as a suspect.

Our sources say detectives are being assigned to research … however no arrests have been made.