R&B singer Tamar Braxton is caught up in a legal battle over her 2013 track One On One Fun.

Songwriter Emmi Kozulin is suing over allegations her vocals were used without permission on the recording, which appears on Braxton's 2013 album Love and War.

In the lawsuit, Kozulin claims she co-wrote the track with Angela Hunte, who had the rights to licence the lyrics but not her vocals.

She is now demanding 50 per cent of the song's royalties, as well as unspecified damages.

A representative for Braxton has distanced the singer from the legal battle, telling Tmz.com it has "nothing to do with Tamar".