British pop star JESSIE J has spoken of her sadness after a young British fan she performed with lost his fight for life following a battle with a rare blood cancer.

The Price Tag hitmaker invited seven-year-old Daniel Sullivan to sing with her after learning he had been diagnosed with acute myeloid leukemia last year (11).

Sullivan died last week (ends04Nov12), and Jessie J has shared her grief with her Twitter.com fans.

The star has uploaded a photo of the youngster on to her page and writes, "RIP Daniel. I will never forget meeting you and us singing on stage together. Never forget you dude."