Amanda Seyfried thinks Hollywood is ''full of petty bullies''.

The 'Mean Girls' star has insisted it is important for people to ''watch your back'' when they get involved in the film industry.

She shared: ''This industry is just like every other industry.

''It's full of petty, spoiled bullies, as much as it is full of wonderful, passionate, honest people... you just have to watch your back.''

The 29-year-old actress offered her advice to aspiring actors and directors.

She added to MTV: ''You just have to be headstrong and believe in yourself, and know that there are people like that who will stab you in the back - just like high school.''

Meanwhile, Amanda proved she doesn't take the negative things people say to her to heart when she revealed she regularly reads Twitter abuse written about her.

She said previously: ''You can't take yourself too seriously if you don't wanna die. So yeah, sometimes I read the feed on Twitter where people are talking about me. I was scrolling one day, and there was something really sweet, like, 'Amanda heart heart' and a picture of me.

''And then there was, 'All movies starring Amanda Seyfried are definitely going to be awful.'''