Miley Cyrus has quit smoking marijuana.

The 'Malibu' singer used to be open about her drug use, but she insists she has been sober for weeks because she wants to be ''clear-headed'' and doesn't see herself as a spokesperson for legalising the herbal substance.

She said: ''I think if people told me to, I wouldn't do it.

''For me, I wanted to be clear-headed -- it's part of living in the moment.

''There are many intelligent and inventive people who are marijuana activists but, for me as an entertainer, it doesn't allow me to have as much energy as I'd like to have or to focus on my work.

''I really want to be clear about my music and what I am doing.I want everyone else to be as well.''

The 24-year-old singer lives a hectic life with a lot of travelling, but she's found ''peace and sanity'' since moving into the Malibu home of her boyfriend Liam Hemsworth, 27, along with their seven dogs, two pigs and two miniature horses.

She told The Sun newspaper: ''I've found my peace and sanity there.

''I surrounded myself in dogs and I had a pig living on my couch. That made me feel like I was at home.

''Finding that space, being with nature again, having trees, clear skies and sun, has helped. I couldn't find that in LA.

''I have this freedom -- not only in my relationship but because I don't feel so trapped in Malibu.''

And Miley admitted the 'Hunger Games' actor was happy she wrote 'Malibu' about him and their relationship.

She said: ''It's about where I am in my life and my relationship. It's just so literal about where we are that it's kind of cool for Liam. Though, he's been the inspiration for many songs.''

But the 'Wrecking Ball' hitmaker laughed off speculation she and Liam are planning to tie the knot soon.

She said: ''It's crazy. Every day someone knows something about my life that I don't.

''Right now my priorities are my music and working on 'The Voice'. As two young people, we have an idea of what commitment is to one another.''