Kim Kardashian's bottom is "like a water bomb".

The US reality TV star invited Australian talk show host Chrissie Swan to grab her rump in order to prove its authenticity live on television, prompting her to compare it to a soft, water-filled balloon.

Referring to her behind, Kim said: "While I've been here, a few people have asked if it's real, so you can grab it if you want."

Chrissie duly obliged and proclaimed: "It's juicy and real! It's like a water bomb. "

Kim questioned: "Maybe a little too juicy?"

But 'The Circle' host disagreed, saying the reason many people admire the former 'Playboy' model is because of her natural looks.

Kim recently appeared naked in a photoshoot for Harpers Bazaar magazine, and said she felt more comfortable than when she appeared in Men's magazine 'Playboy', and is proud that she is seen as a role model to younger girls

Kim, 29, said: "It's definitely scary, but it's very liberating. I think the message is embrace your curves and who you are. I feel proud if young girls look up to me and say, 'I'm curvy and proud of it now.'

"I might have a little bit of cellulite. I might not be toned everywhere. I might struggle in this area or that."