When Grand Theft Auto IV went on sale this week the Office of Film and Literature Classification started getting phone calls.

Not from members of the public concerned about the level of objectionable content in the smash hit video game, but from frazzled staff at gaming shops. "They were saying, 'What do we do?'," says chief censor Bill Hastings.

The shop assistants' dilemma was how to say no to parents demanding to buy Grand Theft Auto IV with their 14-year-old beside them.

The Office's advice was to stand firm. "If it's perfectly obvious the parent is buying the game for the child, don't sell it to the parent," says Hastings. "If a game is R18 it's R18 for a reason and it's illegal to make it available to anyone under that age."

It's possible the adults buying the game for minors are unaware that they could face three months in prison or a $10,000 fine for their actions. Or perhaps they're thumbing their nose at a law that, although it's been in place since 1994, has yet to be enforced against parents.

But Hastings argues fear of being caught shouldn't be the driving force here, it should be doing the right thing - especially for your kids. The game gets its R18 rating largely because of its violence and, thanks to advances in game software and hardware, because it is very realistic.

"When the violence does happen in Grand Theft Auto, it is of a quality that makes it R18 - the degree of it, the intensity of it, the realism of it," says Hastings. "When you shoot a body it reacts in a very human way. It's not just stickmen falling over. It looks real."

There's also a lot of offensive language and some sex. "Sexual matters are not a dominant theme of the game although their presence indicates the game is adult in nature," says Hastings reading from the Office's classification report.

In the version submitted for classification here, the sex scenes include going to a strip club and getting lap dances. There's also another point where the player can have sex with a prostitute - but in the version sold here, there is no visual depiction, just audio.

That's because the game's developers, Rockstar, submitted a specially edited version of the game to the Australian censor - the same edited version that's sold here. Oddly, in Australia, the game gets an MA15+ classification (not suitable for under 15s) - the highest rating, other than banning, the censor can give to video games there. Even with the edits, our censor still rated the game R18. "You have to ask Australia whether they are expanding the upper limit of their MA15+ category to accommodate games that would better deserve an R18 classification," says Hastings.

But unlike banned games such as Manhunt, Reservoir Dogs and Postal, Hastings says Grand Theft Auto does have some redeeming qualities. "With the games we ban you have to kill everyone you meet and you're generally rewarded for making the killing more gruesome. In Grand Theft Auto, you don't have to kill everybody you meet - you could drive around and just look at the architecture."