Taylor Swift backs Dover Police's dash cam tribute

Taylor Swift has backed a US police officer whose version of her song Shake It Off has become a YouTube hit.

Dover Police posted the video online on Saturday, gathering 13 million views in 48 hours. The singer re-tweeted the video, complimenting the officer on his "sass".

The video was produced by the Delaware force using a dashboard camera, and sees the officer lip-syncing, pausing to acknowledge passing motorists.

Courtesy Dover Police Department