Stellan Skarsgard plays Father Merrin in Exorcist: The Beginning

Exorcist: The Beginning is set before the 1973 original, which is regarded as one of the most thrilling films made.

But the prequel used three directors, was totally reshot because it was too tame at first, and final director Renny Harlin was injured by a car on set.

Critics did not get advance screenings, fuelling speculation it will be a flop.

Exorcist: The Beginning was first announced in 2001, with director John Frankenheimer and actor Liam Neeson on board.

Exorcist 'curse'

But Frankenheimer pulled out a month before he died in 2002, with Raging Bull and Taxi Driver screenwriter Paul Schrader taking over.

The prequel's cast and crew were at its premiere on Wednesday

Swedish actor Stellan Skarsgard replaced Neeson in the lead role of Father Merrin - but film studio Morgan Creek did not think the finished movie was scary enough.

So it replaced Schrader with Harlin and changed most of the cast, but Skarsgard stayed in his role.

Then the whole film was shot again.

"The first one we did was more of a psychological thriller, basically about a man in crisis," Skarsgard said.

"For the Renny Harlin movie I changed the performance, I even changed the make-up.

"I think I went much darker in the Schrader version."

During filming, Harlin was hit by a car in Rome and spent the rest of the shoot on crutches with bones in one leg held together by 14 metal pins.

Harlin said he took talk of an Exorcist curse seriously. "It's not very funny, if you think about it," he said. "I believe in it."

'Unintelligible mess'

On the film's US release, there is anticipation but low expectations for the film's quality.

Only a handful of reviews have appeared.

David Germain, a movie writer for the Associated Press, described it as a "cinematic abomination that's about as bad as you could possibly imagine a prequel to The Exorcist might be".

He said: "Three-fourths of the movie is boring as sin, the other quarter is loud, crude and awash in repugnant imagery."

The romanticmovies.about.com site said it was "in strong contention for worst movie of the decade".

"The Beginning is a disjointed, unintelligible mess that's a very poor relation to the classic," it said.

Exorcist: The Beginning is the fourth Exorcist movie, with two sequels released in 1977 and 1990.