Kelly Clarkson has cancelled the remaining dates of her 'Piece by Piece' tour.

The 'Stronger' hitmaker, who is expecting her second child with husband Brandon Blackstock, says she's ''truly sorry'' to have to scrap all of her concerts in the UK and Canada this year after being placed on ''vocal rest'' by her doctors.

Announcing the news, the 32-year-old singer said: ''I am truly sorry that I have to cancel the remainder of my tour dates. I was so looking forward to sharing this tour with all my amazing fans in Canada and the UK. Unfortunately my doctor is telling me I have to stay on vocal rest, but I am working hard to get better as fast as possible.''

Earlier this month, Kelly, who already has 14-month-old daughter River Rose, expressed her frustration on Twitter after she was forced to cancel the last six dates of her US tour due to vocal strain.

She tweeted: ''So bummed that I have to cancel some of my tour dates. This kills me, but doctors are saying I need to rest my voice! I can't wait to get healthy and see y'all back on the road soon. I hate cancelling and I am truly sorry to my fans that have been excited to see this show. Please know that I never cancel anything unless it's absolutely necessary.''

The 'Run' hitmaker lost her voice after giving birth to River last year and previously admitted she feared she would never be able to sing again.

She said: ''I literally had a moment where I cried and drank wine all day. I was like, 'Oh, God, I'm not going to be a singer anymore!' I was bawling to my husband and like, completely hammered, just going, 'Oh my God, it's over. I don't know what I'm going to do.''