Oscars ceremony security 'on high alert in wake of mass shootings', reports claim

Law enforcement sources reportedly told the TMZ website that there is an 'extra knot' in security this year, following the shootings in Sandy Hook and the killings by former police officer Christopher Dorner. (AP)

Los Angeles law enforcement is on 'high alert' ahead of tonight's Oscars in the wake of a wave of gun violence in the US, unconfirmed reports claimed today.

The LAPD has said it is always vigilant during the ceremony, but some reports ahead of the biggest night in the film industry calendar suggest security is at a higher-than-usual state of preparedness.

Law enforcement sources reportedly told the TMZ website that there is an 'extra knot' in security this year, following the shootings in Sandy Hook and the killings by former police officer Christopher Dorner.

One of the sources told TMZ: 'When someone from the city gets fired, the city manager of the department calls because they're scared the person who was fired will go postal.

'People are going crazy with fear.'

Some reports have claimed that the LAPD is handing out dossiers on stalkers who have targeted stars who will appear at the ceremony.

Dozens of the stars of the 85th Academy Awards have already been rehearsing for their big night.

Some dressed down in jeans and hoodies, while others were already in their smartest suits, or chic dresses and spiky stilettos, but they all seemed excited to be part of the big show.

They paraded through the Dolby Theatre at 15-minute intervals - Meryl Streep, Ben Affleck, Reese Witherspoon, Richard Gere, Jennifer Aniston, John Travolta, Jack Nicholson and dozens more.

Catherine Zeta-Jones was also present, as she prepares to join other stars in a tribute to the revival of interest in big-screen musicals.

Those taking part rehearsed their lines in front of an audience of show workers and awarded prop Oscars to rehearsal actors.

They also searched the theatre from the stage, searching for where their seats will be.