Kristen Stewart and Rupert Sanders couldn't keep their hands off each other in Los Angeles last week.

The pair were spotted indulging in a series of passionate embraces by a photographer who said the 'Snow White and the Huntsman' director was ''all over'' his leading lady.

A source told Us Weekly magazine: ''He was all over her'' while another source added they ''would only take a break [from kissing] when they thought someone was walking by''.

A photographer followed Kristen, 22, from her Los Feliz home on July 17, when the actress pulled into the parking lot of a deserted building and Rupert, 41, got into her car.

The source explained: ''It seemed like they couldn't get enough. Kristen was sitting up with her back against the driver's-side window, and this guy was kissing her entire body.''

The pair left when they thought they were being watched and drove to an area near the Hollywood sign and Kristen appeared ''swept up in the moment'' as they kissed and cuddled outside the car.

While the area they were in was quite deserted, they were Disturbed by some dog walkers and each time ''as soon as they heard a voice, they would split up and walk in opposite directions''.

Kristen has been dating 'Twilight Saga' co-star Robert Pattinson for almost four years while Rupert has two children with wife Liberty Ross.