Kristen Stewart's racy birthday gift

Actress Kristen Stewart received a motorbike for her 21st birthday. Photo / Supplied

Kristen Stewart received a motorbike from the cast and crew of the Twilight Saga to celebrate her 21st birthday.

The actress - who plays Bella Swan in the franchise opposite real-life boyfriend Robert Pattinson, who stars as vampire Edward Cullen - reached the milestone age on Saturday and was presented with the gift in Vancouver, where she is currently shooting the final two movies in the series, the two-part Breaking Dawn.

A source told UsMagazine.com: "Rob was so excited for Kristen and they each took turns riding it. Kristen learned to ride a dirt bike in New Moon so they thought it would be appropriate. Rob was supervising as she sat on it to make sure she was OK. They looked like they were having a great time, and it will be something they can really enjoy."

Kristen was also treated to a party by those working on the film on Saturday night and onlookers revealed she was "embarrassed" to be the centre of attention.

A source said: "Rob led the crowd singing for her, and you could tell she was so embarrassed but in a cute way! Everyone was in a good mood, but it was a bittersweet night (as filming is almost complete).

"Rob and Kristen were together all night. They held hands and he kissed her cheek a bunch of times."

- BANG! Showbiz