According to the reports, Will.I.Am's song 'Scream and shout' was originally written by Contostavlos as 'I don't give' in collaboration with her close associate Jean Baptiste.
But when Will.I.Am, who is a member of Black Eyes Peas, heard the song, he took some parts of it and released it featuring pop star Britney Spears, reported Sun Online.
"The song was due to be Tulisa's third single from her album until Will told his protege Jean that he wanted the beat for him and Britney.
"Tulisa's team thought it was a surefire hit but, after losing the battle for the rights, they were forced to release 'Sight of you' which only got to No 18. She now has to watch on as the song goes top 5 around the world," a source said.
Contostavlos, 24, has now dropped plans to release her version.
"At one point Tulisa was even considering releasing her version to rival 'Scream and shout', but now it's unlikely to see the light of day unless it gets leaked," the source added.