Miley Cyrus has said Katy Perry has been her friend the "longest".

Miley Cyrus

Miley Cyrus

The 24-year-old singer has been friends with the 'Bon Appétit' musician for almost a decade, and has said that in Los Angeles that's a "really long time" to stay close to someone, as people often drift apart due to their hectic lives.

She said: "She's been a friend of mine for a really long time. We were actually just realising the other day that next year, we'll have been friends for 10 years. I think that's my friend that I've known the longest. Which is really, really weird! That's like a really long time [in L.A]."

The pair first struck up a friendship in 2008, after the Katy claimed her hit single 'I Kissed A Girl' was written with Miley in mind, and invited the younger star to the MTV Video Music Awards (VMAs) with her.

Miley recalled of the day she found out about the song's meaning: "When she came out with 'I Kissed a Girl,' I was doing the 'Hannah Montana' movie, and I heard her on the radio. They said, 'Who did you write that about?' She said me!

"I screamed and started freaking out, and then she asked me to go to the VMAs with her. That's when I started doing my whole VMA controversy. I was like, 'I'll go with Katy Perry!'"

And the 'Wrecking Ball' singer insists their friendship has remained strong ever since.

She told WKTU Radio's 'Cubby and Carolina in the Morning' on Tuesday (16.05.17): "So, that's how we met, and we just stayed friends."

Meanwhile, Miley recently admitted that she's been clean from drugs for 10 weeks - after first giving an interview at three weeks of sobriety - and has more "energy" since she stopped smoking marijuana.

She said: "At [the time of the interview] it was like three weeks, now it's like nine weeks or 10 weeks or something. Everyone always hits me up. A lot of people have reached out to me and [asked if I want help]. And I'm like, 'No, when I want something, I can do it.' Anything that I want to do, if I want to stop or start something, I can do anything. I just decided not to anymore and now it's easy for me.

"It's very weird. I've got a lot of energy. I'm a very obsessive person, which I need to work on, but also it helps in my position to be a little obsessive because then I can really get things done and make sure it's perfect."