Katy and Ri Ri have been inseparable since the Chris Brown 'incident', but is a collaboration on the cards for the NBFs?

Katy Perry let it slip that there could be plans to work with Rihanna on a new single. When asked if she would like to collaborate with her mate, Katy said: "I wouldn't mind!"

Now, we're not exactly music industry executives, but we're pretty sure that's a green light for the coolest collaboration since, well...Justin and Ciara?

Katy has been hanging out with Rihanna for a few months now and the pair have been to parties, shopping and even on a girly holiday together. 

But Katy isn't ready to start blabbing about Rihanna's 'assault ordeal', as she said: "I think people don't really know the situation of what's going on unless they're in the situation. ... I think it's respectful to not even talk about it." Ooops, sorry girls!

However, she did let on that despite the ongoing Chris Brown court case, Rihanna's keeping her chin up and getting on with her life.  She said:  "She's happy. Happy girl. ... She's smiling."

Katy's the kind of girl we'd love to have as a bessie mate, especially when there's girly trips to Barbados involved!  Katy gushed: "I'm trying to always be there for my friends. She's a really cool chick. I love her style."

So, will the pop diva duet take off?  We hope so, as we need some new music from the girls, sharpish!