The Office of Film and Literature Classification has revealed that it investigated 669 complaints in 2004-05, compared with 361 in 2003-04.
Computer games sparked the highest volume of complaints, with 153 submissions urging a new (R18+) classification be introduced to allow games involving more sex, drugs and violence.
Federal Attorney-General Philip Ruddock also intervened to demand a tougher classification than R18+ for the film Anatomie de l'enfer, which featured actual sex scenes, following a complaint from South Australian Attorney-General Michael Atkinson.
A series of "misleading" reports that Nicole Kidman's movie Birth, rated MA15+, featured her in a sexual relationship with a minor also sparked anger.
The movie had Kidman playing the role of a wealthy widow who was planning to remarry before being confronted by a 10-year-old boy claiming to be the reincarnation of her husband.
OFLC director Des Clark said the board remained strongly committed to the principle of protecting children from material likely to disturb or harm them.
"It is inevitable that some films classified R18+ will be offensive to some sections of the adult community," he said. "However, there are appropriate safeguards in place to ensure that children are not exposed to these films.
"Few complaints were received from consumers who had viewed these films, although a significant number were received from those who apparently had not."
Most of the complaints related to the movie Closer, a tale of adultery starring Julia Roberts and Jude Law and rated MA.
Parents also complained about sex and violence in Bad Santa, an MA-rated comedy starring Angelina Jolie's ex-husband Billy Bob Thornton, and about the violence in the children's film The SpongeBob Squarepants Movie.
The classification board's annual report also revealed it banned almost 20 films or publications because they involved incest fantasies, child pornography, rape, sexual violence and offensive fantasies or fetishes.
The Gore Gore Girls movie was refused classification in Australia as a result of excessive and sexualised violence.
There were almost 100 complaints over videos and DVDs for sale or hire, including concerns that the MA15+ classification for Lost in Translation, House of 1000 Corpses and Texas Chainsaw Massacre was too low.
Parents also complained that film trailers to promote Star Wars: Episode III were shown before children's films.
The OFLC also refused classification for the computer games Singles Flirt Up Your Life and Leisure Suit Larry: Magna Cum Laude because of sexual activity.
The computer game Narc was banned because of drug use related to an incentive or a reward.
Written by Samantha Maiden