Leona Lewis has shot back at claims that she is involved in the Chris Brown and Rihanna bust-up which occurred on Saturday night.

The Bleeding Love star was spotted chatting to Chris Brown at a pre-Grammys party on Saturday, only hours before the alleged assault against Rihanna took place.

A source told the Daily Mirror, "Rihanna saw Chris flirting. He and Leona were laughing and Rihanna saw his hand on the small of her back.

"It was totally innocent but it set Rihanna off.

"Leona is very happy with her boyfriend Lou and it was totally innocent on her behalf. There was no flirting."

Leona's rep added, "This has nothing to do with Leona."

TMZ is also reporting that jealousy was at the root of Chris' domestic abuse, after the Umbrella star found a text message from another woman. 

See the couple at happier times below