Katy Perry reportedly "raced" from a room screaming after she thought she'd seen a ghost.

The singer was in a mansion in Beverly Hills shooting a commercial for her new perfume when the incident occurred. She had been on her own in the master bedroom when she shocked staff by running from the room shrieking at the top of her voice.

"Shivering and terrified, Katy told producers that whole she was alone in the master suite, she turned to the mirror - and froze when she saw a man sporting a moustache staring back at her, his face contorted in agony," an insider told National Enquirer.

"Katy raced from the room and down the enormous staircase, screaming at the top of her lungs! Everyone tried to calm her down."

Security was quick to flock to Katy's room to check things out. They gave it a thorough sweep but didn't find anything, much to her amazement.

"She told them that she would not return to that room - and wanted to get out of the house immediately," the source added.

The director decided to have a chat with Katy, explaining it would be hard to move to a new set. He suggested covering up every mirror in the property and ensuring the star always had security with her, which Katy eventually agreed to.