Britney Spears, Paris Hilton and Pamela Anderson are among the host of stars barred from attending the Oscars this weekend, to reportedly prevent the evening from turning into a "downmarket scrum".

"Britney would have wanted her entourage with her, but the Academy wanted to keep things as tight and as highbrow as possible," a source was quoted by celebrity portal Femalefirst as saying.

"They plan to focus on those people who have worked in the film industry for years - not people who are merely celebrities in other areas."

But other sources said the decision to ban certain stars was because Hollywood's Kodak theatre holds less than half the capacity of the previous venue, the Shrine Auditorium.

Even high-profile stars are reportedly struggling to secure tickets for Sunday's event.