Canadian folk legend Joni Mitchell made a rare, surprise appearance in Toronto, Canada on Tuesday night (18Jun13) — at her own early birthday bash.

A host of musicians, including Rufus Wainwright, Glen Hansard and Kathleen Edwards, had gathered at Massey Hall to perform songs from Mitchell's back catalogue in celebration of her upcoming 70th, and the iconic singer/songwriter, who was expected to make an appearance to recite a new poem, stunned fans at the Joni: A Portrait in Song event when she picked up the microphone and treated them to renditions of Furry Sings The Blues and Don't Interrupt The Sorrow.

Explaining her absence from the spotlight, Mitchell told the audience she has been "kinda out of it" due to "health problems", but stated, "Tonight I must say I feel greatly honoured. I wasn't sure if I could sing tonight. I'm still not sure, but I'm going to try."

She also revelled in the celebration of her milestone birthday and thanked the array of artists who had recreated her tunes for the special concert, stating, "They've been so true to the arrangements but they brought something of their own to it. Isn't this a wonderful collection of talent?"

Fans later treated Mitchell to a group rendition of Happy Birthday and after the applause died down, she said, "Thank you, thank you. This is so much fun."

The singer will mark her actual birthday on 7 November (13).