Singing sensation Rita Ora has opened up about a secret romance she shared with Bruno Mars before either of the pair hit the big time with their music careers.

According to the Sun, the 21-year-old beauty - who is currently dating Rob Kardashian - had a fling with the crooner when he was brought in by her record company Roc Nation to write some songs for her.

She revealed it was "love at first sight" and called the relationship a "great experience", admitting they came under strain after finding fame and enduring hectic schedules that kept them apart.

Ora said: "He was a struggling songwriter hired to write songs for me. I thought, 'Wow, that's just the world's greatest guy!'"

Photographs of the pair at Berlin Airport were published in 2011, sparking rumours about the pair's relationship, which - Ora claimed - was around the same time they decided to part ways.