Rob Kardashian is being sued for alleged robbery and assault.

The reality TV star has been hit by a lawsuit from photographer Andra Vaik, who claims Rob assaulted her and stole part of her camera equipment last month - all because she tried to take a shirtless picture of him.

Andra Vaik's lawyer told TMZ: ''While this case is still in the preliminary stage, it is clear from our investigation that Robert Kardashian's violent behavior and his use of force towards Ms. Vaik was completely unjustified.''

Rob - who has been struggling with his weight ever since breaking up with singer Rita Ora last December - insists the paparazzo was trespassing on private property in order to get the money shot.

He says he was justified in snatching the memory card out of the camera, with eye-witnesses backing up his claim the photographer was lying in wait in her car in the garage at his West Hollywood gym.

Andra filed a robbery report at the time, despite Rob insisting he would pay her back.

The 26-year-old star has set himself the target of losing 50 pounds before July 4 by exercising twice a day and sticking to a low-carb diet in order to attract ''beautiful women.''

He confessed last month the breaking point came when he became upset by how his naked body looked when he took a shower.

Rob sighed: ''Every time I hop in the shower and see myself naked I cry, because my penis looks so small. The upside is, every time you lose 10 lbs you gain an inch on your penis.''