Former Conservative party leader Iain Duncan Smith has joined the ranks of critics attacking the 12A rating given to The Dark Knight.
The British Board of Film Classification (BBFC) was forced to defend the film's classification on Monday after more than 80 complaints regarding its content were received.
And Mr Duncan Smith, MP for Chingford and Woodford Green, has now professed his 'astonishment' at the certificate handed to the record-breaking Batman Begins sequel.
In a letter to the Times newspaper, he expresses his concern that the BBFC may have bowed to pressure from the film's production company Warner Bros to keep its rating child-friendly in order to maximise profits.
He wrote: "Unlike the past Batman films where the villains were somewhat surreal and comical figures, Heath Ledger's Joker is a brilliantly acted but very credible psychopathic killer how extols the use of knives to kill and disfigure his victims, during a reign of urban terrorism, laced with torture.
"It is a relentlessly violent film, filled with dark themes, and as I left I wondered what the board could possibly have been thinking."
In response, a statement on the BBFC's website maintains that the film's rating is appropriate to its genre.
"The Dark Knight is a superhero movie and the violence it contains exists within that context, with both Batman and The Joker apparently indestructible no matter what is thrown at them," it said.
The statement follows comments by the BBFC's spokeswoman Sue Clarke who said that a total of 82 complaints is an acceptable return for a film which has now been seen by 4.7 million Britons.