A youth has been charged over an armed robbery at a Mowbray business overnight. 

Police were called to Invermay Road about 5.45pm Saturday after reports a person was in possession of a knife and had threatened a staff member before stealing items and leaving the scene. 

A 15-year-old girl was arrested a short time later and charged with armed robbery. 

Nobody was physically injured during the incident. 

The youth was held in custody to appear in the Youth Justice Division of the Launceston Magistrates Court today.