(Cover) - EN Showbiz - Rihanna has been taken to hospital for an unknown condition.

The Barbadian singer was due to perform in Sweden tonight but has had to cancel the show.

Although she is too ill to be on stage, the 23-year-old took time out to send a message to her fans on Twitter to apologise for not being able to show up.

"Sorry Malmo!" Rihanna wrote and attached a picture of her arm with a tube coming out of it, said to be an IV drip.

A representative for the tour promoter Live Nation said the show was cancelled because the singer is "not in condition to conduct the concert."

Rihanna has been travelling around the globe for several months as part of her Loud tour.

She last performed in the Norwegian capital of Oslo on Sunday night.

It is not known if the We Found Love starlet will be up to performing tomorrow in Stockholm as scheduled. (C) Cover Media