British pop star Rita Ora has apologised for "freaking out" her fans after collapsing during a fashion photoshoot in Miami, Florida earlier this week (begs18Nov13).

The R.I.P. hitmaker sparked fears for her health on Monday (18Nov13) after fainting on the set of a shoot for Madonna's Material Girl clothing campaign, which she fronts.

She was briefly hospitalised and treated for heat exhaustion and dehydration, but Ora has now assured devotees she is feeling "much better".

The singer, who has since returned home to London, tells Tmz.com, "It was exhaustion; I was a bit tired. Thank you everyone for worrying, I'm much better now, it'll never happen again... Sorry for freaking everyone out."