Movie piracy is thought to cost the industry $3bn a year

The most high-profile front of the campaign is an advert made by the Motion Picture Association of America (MPAA) that is currently being shown in cinemas across the US.

The advert is intended to put across the message that piracy damages movie production. It is designed to make people aware of the consequences of piracy and to try to discourage would be copiers.

"The digital era has been fantastic for the industry and is actually keeping the film industry in very good shape, because the revenue growth is in DVD," Steven Gaydos, executive director of film magazine Variety, told BBC World Service's Analysis programme.

"That's the explosion right now that is making Hollywood very happy.

"But at the same time there is an awareness that the digital genie is out of the bottle, and everyone is watching very nervously because they see DVD has opened up possibilities for pirating that didn't exist before.

"The rise of broadband is even more ominous."

Revised schedules

Broadband makes it much easier to download films via file-sharing services or from websites.

Prior to DVD piracy was limited to a national problem. Now we've got a global epidemic Neil McEwan, Warner Home Videos Piracy 'threat' to Hollywood

Illegal copying is already happening on a massive scale, studios argue, hence the need to tackle the problem now before it gets any bigger.

"The launch of DVD in the last five years has given the opportunity for global pirates to start getting involved in the business," Neil McEwan, Managing Director of Warner Home Videos in the UK, told Analysis.

"Prior to that piracy was limited to a national problem. Now we've got a global epidemic.

"At the moment we think piracy is running at a level between 20% and 30% of the entire size of the legitimate market."

In recent weeks the US recording industry has begun suing hundreds of individuals accused of downloading songs over the internet without paying for them.

Figures show that the sale of compact discs has declined by 30% in the US since 2000. The music industry says this is largely due to the unauthorised swapping of music over the net.

The slump has left film executives fearing their multi-million dollar industry will be next once faster internet connections such as broadband become widely available.

Armed guards

Studios are so concerned because DVDs of films have, in recent years, boosted the revenue of US studios - who last year made $30bn from sales of the discs.

FIGHTING THE PIRATES Lower price DVDs Simultaneous worldwide movie releases Crackdown on illegal recording in cinemas Reduced cinema-to-DVD time Tracking online movie file-swappers Advertising campaign

The MPAA says piracy has a two-fold effect on revenue, and cites Star Wars Episode One - The Phantom Menace as an example.

Both film and DVD/video revenue in Asia was dramatically hit, they say, because illegal copies of the film made by people with camcorders in the US were widely available in the region, before the film was released there.

To combat this, US cinemas are now employing armed guards equipped with night-vision goggles at screenings to spot anyone attempting to illegally record the film.

At the same time, security firms are being deployed to try to track down internet hackers.

Lower prices

Hollywood's battle against the pirates is also changing film schedules around the world.

Lord Of The Rings: Simultaneous worldwide releases

"The movie industry is trying to shrink down the time between when a movie is in theatres and it goes to DVD to reduce piracy," said Mr Gaydos.

"They're looking at getting movies out across the world faster in more theatres."

While Star Wars Episode One had a staggered release, UK cinemas got Episode Two only a week after its US release. The Lord Of The Rings films have been released simultaneously worldwide.

Additionally, Mr Gaydos said, studios were trying to deter people from piracy with the most powerful weapon of all - cash.

"They're bringing down the prices of DVDs," he argued. "I think that's directly or indirectly related to piracy.