Katy Perry has offered her condolences following the death of a 16-year-old girl whose cover of Roar became an Internet hit.

Cancer patient Olivia Wise became an online sensation earlier this year (13) after a recording of her singing Perry's popular track hit the web, and the pop star was so moved, she recorded a special video message for the teen.

Wise, who was suffering from a brain tumour, passed away on Monday (25Nov13), and Perry was quick to remember the youngster for her bravery.

In a post on her Twitter.com page, she writes, "Olivia Wise, I can hear you singing with the angels now. Your spirit + strength has inspired me + so many others... May you rest in peace."