A Nevada based woman from the USA in a lawsuit has accused Portuguese football star Cristiano Ronaldo of raping her in a Las Vegas hotel in 2009.

Kathryn Mayorga says she was attacked by the Juventus footballer in a hotel room in the US city that year and police in Las Vegas have reopened a sexual assault investigation now at her request.

According to the lawsuit, Mayorga, who was then 24, went with a friend to the Rain nightclub at the Palms Hotel and Casino on the night of June 12, 2009 and met Ronaldo there.

He invited a group of people up to his suite "to enjoy the view of the Las Vegas strip" and then into the hot tub. Cristiano then barged in on her as she was changing, exposed himself and asked her for oral sex. When she refused, the lawsuit claims, he raped her, the lawsuit claimed.

However, she reportedly reached an out-of-court settlement with Ronaldo involving a USD 375,000 payment for agreeing never to go public with the allegations.

The 33-year old footballer refuted the claims and posted a video on Instagram saying, "Fake. Fake news".