Demi Lovato's rep has dismissed rumours that she is engaged.

The singer has been linked with on-off partner Wilmer Valderrama and she turned heads recently by uploading an Instagram photo of herself wearing a ring.

She then added a collage of photos of herself with the actor, saying:

"To the funniest, most inspiring, incredible man I know.. @WValderrama - thank you for helping me get through my darkest moments.. You truly are a light to this world and to my life.. Happy Birthday!!!"

This led some people into believing the couple are now engaged - but a rep for Lovato insisted that this isn't the case.

The singer meanwhile is due to head out on her Neon Lights North America tour soon, with her first date taking place in Vancouver on February 9.