Cristiano Ronaldo won’t face criminal charges after a woman accused the football superstar of raping her in his suite at a Las Vegas resort more than 10 years ago, the city’s top prosecutor says.

Clark County District Attorney Steve Wolfson said he reviewed a new police investigation and determined that Kathryn Mayorga’s claim can’t be proven beyond reasonable doubt.

“Therefore, no charges will be forthcoming,” Mr Wolfson said on Tuesday.

Ronaldo’s lawyer, Peter Christiansen, was travelling this week and not immediately available to comment. Mr Christiansen has previously said Ronaldo and Mayorga had consensual sex in 2009. He denied it was rape.

Attorneys for Ms Mayorga, a former model and schoolteacher, did not immediately respond to telephone, text and email messages.

The Associated Press generally does not name people who say they are victims of sexual assault. Ms Mayorga consented through her lawyers to having her name released.

She has a lawsuit pending against Ronaldo in US court in Las Vegas that accused Ronaldo, or those working for him, of conspiracy, defamation, breach of contract and coercion and fraud.

Ms Mayorga says they allowed terms of a confidential financial settlement with her to become public.

Ms Mayorga’s lawyer, Leslie Mark Stovall, has acknowledged that Ms Mayorga received $US375,000 ($A532,767) in hush money following the encounter.

He maintained that agreement was made under pressure from “fixers” trying to protect Ronaldo’s reputation.

The lawsuit seeks to void the agreement and collect at least $200,000 more from Ronaldo.

Ronaldo, who plays in Italy for the Turin soccer club Juventus, is one of the most recognisable and highly paid sports stars in the world.

Ms Mayorga had a medical exam to collect DNA evidence shortly after she says Ronaldo assaulted her in June 2009.

She spoke to police again for the new investigation, and authorities this year obtained a sample of Ronaldo’s DNA through Italian authorities.

Police said the initial investigation was closed in 2009 because Ms Mayorga identified her attacker only as a European footballer, not by name, and did not say where she claimed the rape took place.

The investigation was reopened in last year at the request of her lawyers, shortly before they sued Ronaldo.

-AAP