Rihanna "difficult" to work with?

'Beneath Your Beautiful' hitmaker Labrinth says Rihanna may not be as chilled out as she likes to portray, claiming she was "difficult to work with" on her new album Unapologetic.

The 22-year-old, who is signed to Simon Cowell's record and has released several top 10 singles, lent his producing skills to 'Lost In Paradise,' a track which features on Rihanna's chart-topping seventh studio album.

Rihanna spent a considerable amount of time in the UK this summer performing at various festivals and recording the record, and drafted in Labrinth to produce 'Lost In Paradise.'

However, Lab says it wasn't the best experience claiming Rihanna may have acted like a diva, describing their time together as "difficult."

"I've finished working with Rihanna on some of her album... It was difficult but we got through it," Labrinth told the Daily Record.

When probed on what exactly was so difficult about working with the Bajan songstress, Labrinth simply replied: "It was just difficult."

We wonder why Rihanna was so "difficult" to work with.