Britney Spears has bought a $45,000 motorcycle for her boyfriend's birthday.

Agent Jason Trawick turns 40 today, and Britney teased on Twitter that she had a "big surprise" in store for him.

It's now been revealed that the songstress has purchased an impressive motorcycle to commemorate his big day. The vehicle is a limited edition luxury bike that cost the songstress a cool $45,000.

"Hbday Jason! He looked so cool in the video, that I had to get him a new motorcycle" she tweeted, with an accompanying photo of the bike.

The motorcycle is a 3rd generation X132 Hellcat, which Britney bought from Confederate Motorcycles a few weeks ago.

She also purchased a $940 leather jacket to accompany the present.

Unfortunately, the bike wasn't ready for Jason's birthday, but according to a representative from the company, it will be delivered to their home very soon.

"I think she made the right choice," Confederate Motorcycles company employee Clay Morrison told RadarOnline. "We couldn't be happier that she chose to share the finest motorcycle in the world with Jason!"

Britney is reportedly one of the first stars to buy the new model of the motorcycle. A host of famous faces own the former model though, including Brad Pitt and Tom Cruise.

Britney couldn't wait to surprise Jason with the gift. The star took to her Twitter page yesterday to keep fans informed.

"Poor Jason he has less than 5 hours left to be in his 30s. I have a big surprise for him tomorrow. Xxoo, (sic)" Britney Tweeted.

Meanwhile, Britney has been getting into the Christmas spirit, with an impressive festive display at her Californian mansion.

The 30-year-old star has decorated the outside of her San Fernando Valley abode with an array of colourful lights.

Britney's Christmas display includes a large inflatable Santa near her doorway.