Seth Rogen's forthcoming movie Zack And Miri Make A Porno has hit a stumbling block - promotional posters for the picture have been banned by members of the U.S. film regulation board.

The upcoming release, directed by Kevin Smith, stars Rogen and Elizabeth Banks as cash-strapped pals who hatch a plan to solve their money problems by making an adult film.

But studio bosses will have to commission a new poster to promote the movie - because the current advertisement, which suggests the characters are engaging in oral sex, has been deemed too explicit by members of the Motion Picture Association of America (Mpaa).

The banned poster features two separate and seemingly innocent images of Rogen and Banks fully clothed. But it's the suggestion they are engaging in fellatio - hinted at by the appearance of the back of Banks' blonde head at the crotch of Rogen, and Rogen's curly crop at Banks' groin - that has prompted the board's decision.

And filmmaker Smith is angered at the ruling.

He says, "When you've got the word 'porno' in the title, naturally, the marketing materials are gonna be scrutinised more closely by the Mpaa. I understand they've got a job to do, but c'mon?this image isn't that dirty; they're both fully clad."