Spider-Man 2 was among the focus of pirates last year

The law aims to clamp down on pirates who sell bootleg copies of new films.

Penalties for people who distribute music, movies or other copyrighted works before their official release have also been tightened under the law.

President Bush is now set to sign the bill, which has been passed by both the Senate and House of Representatives.

Movie studios have welcomed the move, with piracy costing the industry an estimated �3.7bn ($7bn) in 2003.

Hidden recordings

Copies of hit movies have been appearing on the internet and on the black market soon after they debut in cinemas.

Pirates take concealed camcorders into screenings to tape films directly off the screen, while industry insiders leak copies before they are officially released.

The US Customs Department estimates that these two groups are responsible for 95 per cent of all pirated movies available online.

Those found guilty under the new laws could face up to three years in prison, with six year sentences for subsequent offences. They may also face legal action from copyright holders.

Anyone caught distributing a movie or song prior to its commercial release will face up to 10 years in prison.

Filter devices

The bill also protects makers of "family friendly" machines and devices that strip violent or sexually explicit scenes from copyright claims.

The Directors Guild of America had tried to sue manufacturer Clearplay for its DVD scanning device which blocks out explicit content.

The directors' group alleged that the unauthorised changes constituted copyright violations.