Demi Lovato returned to work today (22.03.11).

The 18-year-old star - who left rehab in January after seeking treatment for "emotional and physical issues" in November - is taking further Steps in her recovery, but would not reveal the project she was embarking on.

She tweeted: "First day back to working. I can't wait to share with you guys what I'm doing today.

"It's a big day for me. So excited! I love you all!!! (sic)"

Mystery sounds what Demi is working on as Disney bosses insist she hasn't yet returned to her TV show 'Sonny With a Chance'.

A spokesperson told E! News: "Demi's management will inform us when she is ready to return to work.

"As you know, last November, we announced that we would focus on our 'So Random' sketch comedy show [the show within 'Sonny With a Chance'] to keep the staff, cast and crew employed. We began production in January and will debut those episodes this spring."

Demi - who entered rehab after she allegedly punched a backing dancer - recently revealed she was excited about the prospect of returning to work.

In a video message thanking fans for their support, she said: "I wanted to let you guys know that I'm excited to get back to work and I can't wait to tell you what the future holds. I can't wait to see you guys in person and thank you all individually. I love you all and I couldn't have done this without you."