Her lacklustre and widely-ridiculed performance of Gimme More was followed by a series of problems for the troubled pop star, including losing custody of her two young children.

But the 26-year-old has said she will not sing at this year's event in Los Angeles, but would offer something "fun and unexpected" instead.

Spears said that MTV had "long played an important role in my career" and added: "How can I not be there to kick off their 25th VMAs?"

"I'm excited to open the entire show, to say 'hi' to my fans and to be nominated," she said.

She is in the running for three VMAs, including best video for Piece Of Me.

Before her disastrous comeback performance last year, she made headlines at the 2006 ceremony for her kiss with Madonna.

British comedian Russell Brand, a virtual unknown in the US, will present Sunday night's show from the Paramount Studios in Hollywood.

He said Spears would be "doing something so mind-bending, I think it's going to tease you and probably make you want to start families with each other".

"It's going to be, actually, bloody exciting," he said.