Nick Carter has been accused of sexually assaulting a woman and passing on STDs that led to cervical cancer.

The Backstreet Boys singer has denied allegations made in a lawsuit filed by Laura Penly, who claimed the 45-year-old star sexually assaulted her when she was around 19 years old in 2004.

In documents obtained by People magazine, Laura alleged she and Nick had a "sexually intimate relationship" between December 2004 and February 2005, when they would see each other approximately every few weeks" when she visited Los Angeles.

The woman claimed sex was consensual at least three times before things took a turn at Nick's Hollywood apartment.

Laura insisted she had never had unprotected sex with anyone before but Nick allegedly "refused" to wear a condom, leading her to believe "he was 'clean' of sexually transmittable diseases."

She alleged in early 2005, she returned to his apartment in the hope of watching movies but Nick "told her no because the only reason she was there was to have sex." The plaintiff then alleged a sexual assault "forecefully" happened on his bed, despite her "saying 'no' multiple times."

The woman claimed she was instructed to keep what had happened a secret as no one would believe her anyway but a few months later, Nick - who she accused of having "failed to use protection to prevent the spread of sexually transmitted infections" - is said to have apologised and she saw him again, only to allegedly sexually assault her for a second time.

Nick is accused of having "infected plaintiff with various sexually transmitted diseases, including the human papillomavirus (commonly known as HPV), a sexually transmitted infection known to cause health problems such as cervical cancer."

In approximately July 2005, Laura allegedly tested positive for chlamydia and gonorrhea, plus cancerous cells, and the following month she was "diagnosed with Stage 2 Cervical Cancer and had to undergo numerous treatments," which caused "severe emotional distress, physical anguish, medical issues, intimacy issues, and other complex trauma" for Penly.

The plaintiff is seeking damages in excess of $15,000 due to the 'Quit Playing Games' hitmaker's "willful and conscious disregard" for her safety and is demanding a jury trial.

Representatives for Nick insisted he doesn't remember "ever even meeting" his accuser.

Attorneys Liane K. Wakayama and Dale Hayes, Jr. said in a statement: "This is just more of the same nonsense from the gang of conspirators and their lawyers who continue to abuse the justice system to try to ruin Nick Carter. It's drawn from the same predictable playbook - lie in wait for decades until Mr. Carter is celebrating a professional milestone, then hide behind litigation privilege to make utterly false claims in an attempt to inflict maximum damage on Nick and his family.

"Nick does not recall ever even meeting Laura Penly. He certainly never had any romantic or sexual relationship with her. Ever."

Laura is the fourth woman to come forward and accuse the Backstreet Boys star of sexual assault.