Sky Ferreira has scrapped another gig due to illness.

The singer has been riddled with health woes for months. She was hospitalised with a leg injury while touring with Miley Cyrus in February (14) and has since been battling problems including influenza, a sinus infection and an allergic reaction, and she has axed a number of concerts.

She has now come down with another unspecified illness and dropped out of a scheduled performance at the Firefly Music Festival in Dover, Delaware on Friday (20Jun14).

Ferreira apologised in a post on Twitter.com, writing, "Sorry I had to cancel Firefly Festival due to being ill. Promise I'll play Dover soon."