LATEST: Pop star Britney Spears has been slammed as "wicked" and "sick" for hiring dwarves to entertain her husband's guests at his recent birthday bash.

Spears has been criticized by a host of foundations representing the interests of smaller people, who have branded the stunt at last month's (Mar. 21) surprise event utterly tasteless.

At the party, hosted in a Las Vegas, Nevada restaurant, two female dwarves were reportedly employed to carry in Kevin Federline's 28th birthday cake, while another dressed as a miniature Sonny Bono alongside a Cher look-alike.

Horrified sources claim boozy guests giggled and cheered, with some jokingly suggesting a dwarf-throwing contest.

But dwarf groups are enraged at the appearances, insisting the stunt was demeaning.

A member of America's Billy Barty Foundation - named after the late diminutive Hollywood veteran - says, "It is wicked to hurl abuse at anyone of diminished height simply because they are small.

"We know dwarves and midgets who are immense in stature because of their talent.

"Mostly they are able to rise above any insults. But inevitably, feelings are hurt by nasty comments. There's only one word for it - bullying."