Britney Spears wanted Nicole Richie in her 'Pretty Girls' video.

The 33-year-old star has revealed she was originally eager for the fashion designer to feature in the clip for her new single featuring Iggy Azalea, because she hoped they could be ''valley girls'' together.

Speaking about the video - which premiered last month - she said: ''I actually wanted Nicole Richie to be in it and I was like, 'We could do something really funny, I know her really well, she's a really, really sweet girl and we can be like valley girls' and all of this kind of stuff. But what happened was we got the song from Iggy's producers and it fit my voice so well and then we just ended up doing it and it worked out and then I got the idea of the valley girl thing and it was really cool.''

The track is the first to be taken from Britney's as-yet untitled ninth studio album, and now she has one collaboration under her belt, she admitted she is keen to involve more of her favourite acts on the LP.

When asked whether she has a list of other artists she hopes to work with, she told ITV's 'Good Morning Britain': ''Oh yeah! Ludacris, Gwen Stefani, Pharrell, Shania Twain, Celine Dion. There's so many amazing artists out there.''