Washington, November 4 Twilight co-stars Robert Pattinson and Kristen Stewart appeared to blow the lid on their secret romance after they were seen locking lips outside a screening of the film's sequel.

The pair previously denied the dating reports, insisting they were just "friends".

But rumours reached a new high after the duo reportedly spent the night together at Hollywood's Chateau Marmont hotel last week.

The stars later attended the screening of The Twilight Saga: New Moon where they were spotted kissing.

"Rob wanted a cigarette so he went outside with Kristen for about 15 minutes," Contactmusic quoted a source as telling the Us Magazine.

"They were hugging, as Rob was smoking his cigarette, and then he leaned down and kissed her on the lips. He had his arm around her almost the whole time," the source added. (ANI)