Britney Spears is reportedly set to thrill fans with a surprise set at the American Music Awards on Sunday.

The Toxic hitmaker is rumoured to be taking to the stage at the event at Los Angeles' Nokia Theatre to mark her comeback to the music scene with forthcoming album Circus.

And host Jimmy Kimmel is adamant the event's organisers are planning a spectacular secret performance, but that they won't tell him what it is.

The funnyman tells E! Online, "They have these surprises that 75 people on the crew know about, but they won't tell the host.

"Apparently, there is some big surprise. I sent... the producer an email yesterday and he was like, I can't tell you."

If Spears did play a set at the ceremony, she's be in good company - childhood rival Christina Aguilera, Mariah Carey, Leona Lewis,Taylor Swift and Kanye West are all slated to perform.

But Kimmel is hoping Spears won't make a surprise appearance at the show - because he once upset the singer by locking a Kevin Federline impersonator in a box and dumping him in the sea for a skit at the 2006 American Music Awards - just weeks after the former couple's divorce plans were announced.

The ceremony will be broadcast live by ABC on Sunday.