Kristen Bell says she's terrified - but delighted - to be performing on stage again.

The Frozen star - who voiced Princess Anna in the hit film - is starring in the anti-establishment rock musical Hair in Los Angeles.

The Veronica Mars actress features in three shows at the 18,000-seat Hollywood Bowl amphitheatre, starting on Friday.

"Performing again onstage is wonderful - especially at a venue like the Bowl. It's enormous, dynamic and terrifying," she said. "I never thought I would perform in a place so big!"

The actress, who was in a production of Hair in college, added: "I definitely missed singing live and music in general.

"Music heightens any emotion so it is a wonderful tool to use when performing and storytelling."

Hair, which has book and lyrics by James Rado and Gerome Ragni and music by Galt MacDermot, tells the story of two best friends who find freedom in the 1960s preoccupation with sex, drugs and rock 'n' roll. The hit songs include Aquarius and Let The Sun Shine In.

Kristen, together with Tony Award winner Idina Menzel, made her own monster hits while recording the soundtrack to the animated film Frozen.

She says she's proud she got a chance to sing in such a landmark movie.

"It's hard for me to conceptualise how many people have seen Frozen - it's been such a whirlwind," she said. "I would love it just the same if no one had seen it at all - but the fact that kids are connecting to the idea of choosing love over fear makes me so happy."