Despite her bountiful bank balance and Beverly Hills existence, Paris Hilton has remained a natural beauty and refused to succumb to the lure of scalpels, needles and knives ...

Or has she?

Pop Tarts caught up with the hotel heiress just a couple of weeks ago in Sydney and her lips were looking well — particularly plumped.

"It definitely looks as though she had lip augmentation, probably with a hyaluronic acid like restylane on both lips," Fifth Ave-based cosmetic surgeon and dermatologist Dr. Lewis M Feder (who does not treat Paris) told Tarts.

Famed Beverly Hills surgeon, Dr. Payman Simoni agreed.

"It seems that Paris Hilton has done what is one the most common cosmetic procedures after breast implant and that is the lip enhancement. One tell-tale sign is the white shine at the borders of her upper lip which is usually achieved by injection of Hyaluronic acid commonly known as Juvaderm or Restylane," Simoni said. "In this case of Paris Hilton, her lips would have been more improved if the physician enhanced her cupid bow. But overall, she had a great (apparent) lip enhancement."

Eugenia Shakhnoff, Registered Nurse and aesthetician at West Hollywood’s Ona Spa and Dr. Richard Fleming of the Beverly Hills Institute agreed that it appeared as though Paris had undergone lip augmentation.

However, a Hilton rep denied that the 28-year-old has ever altered her looks surgically.

"She did not do anything to her lips. She has never had any type of plastic surgery whatsoever," Paris's manager assured Tarts.

Click here to see photos of Paris and her (possibly) changing lips through the years.

Hilton also told us recently that unlike all her BFF's in life, she'll never go under the knife.

"I hate needles; I hate blood so I’ve chosen not to have surgery. I’m too scared of waking up in the morning and looking different," Hilton (who played a plastic surgery addict in the cult thriller "Repo! The Genetic Opera") said. "I have nothing against it, living in Hollywood most of friends, actually pretty much all my friends, have had surgery but I like being all-natural."

But on the topic of changing her physical appearance, Paris did debut a hot new hairstyle at Hollywood hotspot Apple on Tuesday night.

Following in the footsteps of Victoria Beckham, Katie Holmes and Gwyneth Paltrow, the stylish socialite showed off her "bob" as she boogied the night away. And according to Pop Tarts spies, the newly-single Hilton was also canoodling with "Days of our Lives" star Darin Brooks in a private cabana.

"They couldn't keep their hands off each other," said the insider.

Victoria Beckham Strips Off For Big Bucks

Last year, David Beckham got down to nothing more than cotton coverings in an underwear campaign for Giorgio Armani, and now wife Victoria has followed suit.

The 34-year-old mama stripped down to lacy lingerie in a series of sultry black & white photos for the high-profile label in a rumored three-year, multi-million dollar deal. She must be boosting the bank balance is quite a prominent way as Posh has said in past interviews that she didn't like her naked body and never thought she could go near-nude.

Click to see.

The super sexy snaps are slated for release in February as billboards across New York, Rome, London, Paris and Tokyo.