Beyonce Knowles never plans to sit down and compose a track with her rapper boyfriend Jay-Z, because their collaborations just happen naturally.

Knowles and the hip-hop star, real name Shawn Carter, have recorded Crazy In Love, Bonnie & Clyde and her latest track deja vu together.

But Knowles insists the duets aren't planned and Jay-Z just added his rap to deja vu after she recorded it.

She says: "This record I had completed and I let him listen just to get his opinion and his lips started mumbling and his mind started thinking and he just thought of the 16 bars of the rap. So I said: 'OK,lets go to the studio,'and he laid it down.

"We never try to sit down and write a song together. It's never forced. I made it - finished it - and then he has an idea ... or he has a record and I'll say can I sing on this record?

"I would be really nervous writing for another artist."