A new Selena Gomez track, 'Sad Serenade', has leaked online.

The song's sad lyrics have sparked speculation it is about her on/off romance with Justin Bieber, who she initially split from at the end of December.

In the track Selena speaks about heartbreak, a lost love and lingering feelings.

Selena sings: '' A sad, sad serenade / Sad serenade / we almost got it right/ A sad, sad serenade...for every broken heart tonight.''

The 20-year-old singer and actress also appears to talk about moving on in the song, with the lines: ''I wish you the best I really do / Even though I'm still not over you / I know that we are both to blame / I can't believe, you didn't fight harder for me.''

While the song is new, it is not thought to be included on Selena's debut solo album, 'Stars Dance', set for release in June.

Selena has previously talked about how she struggles to keep her relationships private.

She said: ''I can't be afraid to live my life...You're young and you don't know how to be. You don't think, 'Now I have a boyfriend - let's keep it super-private and low key', because that's not what you're thinking about.

''Everybody falls in love, and you would never want to hide something you're so happy about.

''But I've learned a lot. You keep the things that are super-private to yourself. I definitely want to do that now. But it's so hard.''