Rita Ora reportedly cheated on Robert Kardashian with Jonah Hill.

The 22-year-old 'How We Do' singer - who split from the 'Keeping Up With The Kardashians' star earlier this month after which he publicly accused her on Twitter of being unfaithful to him - allegedly spent the night with the 29-year-old '21 Jump Street' star while she was still dating the reality TV star.

A source told USMagazine.com: ''Rita spent the night with Jonah during a trip to New York.''

The British singer reportedly met Jonah at a nightclub and went home together but Robert quickly found out.

In now deleted messages on his Twitter account, Rob angrily accused his ex-girlfriend, whom he dated on and off for more than a year, of cheating on him.

He posted: ''She (Rita) cheated on me with nearly 20 dudes while we were together, I wonder how many she will sleep with now that we apart?

''But I mean 20?!!! How can a woman who is so busy trying to start her own career have time to be with so many dudes all while in a relationship?! (sic)''

Rob, 25, added: ''I'm actually disgusted a woman could give up her body to more than 20 dudes in less than a year's time while trying to start a career.''

The pair's separation had been blamed on Rita's hectic work schedule and their incompatible jet-setting lifestyles.