Mystery surrounds Britney, Heidi duet

Britney Spears and Heidi Montag have denied they recorded a duet together.

Britney and The Hills star Heidi's voices both appear on Dramatic - which premiered on Ryan Seacrest's KIIS-FM radio show - but the stars insist they didn't work together on the track.

A representative for Heidi said: "Heidi has no knowledge of this recording. She did do a demo of this song for possible use on her record, but that recording had a male vocal on it, not Britney Spears."

Host Ryan believes the song was leaked by Heidi's camp, adding: "I just opened an email and there was this track and it said, 'Britney Spears and Heidi Montag'. How can you do that?

"If she doesn't know Britney, how can Heidi do a song with Britney? You've got to get a little Britney permission on that I would think."

Meanwhile, Heidi's 24-year-old stepbrother Eric O'Hara - a soldier who has fought in both Iraq and Afghanistan - died on Thursday after slipping off an icy roof at the Steamboat Springs Steamboat Grand Resort Hotel in Colorado as he was removing snow.

Heidi said in a statement: "Losing my brother, at an early age, is such a tragedy. I just loved him more than anything. He was just so patriotic. He really wanted to go to Iraq and help and do all that he could for his country. He felt like it was his duty. I'll really miss him."