Rita Ora has claimed that her partnership with Rob Kardashian didn't work out because she was too busy.

The news comes after Kardashian hit out at the singer on Twitter, alleging that Ora slept with "almost 20 men" whilst they were together.

He said he was "disgusted" that the 'Hot Right Now' star apparently managed to "give up her body" to numerous males whilst starting a music career.

Speaking in Glamour magazine, however, Ora said that they didn't work out because she wasn't able to be with him enough. The singer said:

"I'm not going out with Rob. We were close for a while, but it didn't work because I was never there. I was like a ghost. I used to get so frustrated with myself and then wonder why I was angry, so I decided it was best to keep it friendly - especially at the moment, when there's so much going on."

Ora features on the cover of Glamour's January 2013, with a sultry shot from the accompanying photoshoot shown below.