Singer Lady Gaga has cancelled two shows in the US after being struck down with bronchitis.

The 28-year-old was forced to leave a gig in Seattle, Wednesday and thereafter cancelled a show in Vancouver on the American leg of her 'artRAVE Tour' due to the illness. reports contactmusic.com.

The singer apologised to her fans and took to Twitter: "I'm devastated. I'm unable to perform this week. Ursula (fictional sea witch from 'The Little Mermaid') took my mermaid voice. I've come down with horrible Bronchitis."

Gaga said that she would reschedule the cancelled shows so that the fans could see her live.

"My deepest apologies to Seattle and Vancouver, we'll reschedule those shows and will be back to make it up to you. I love you monsters," she tweeted.