Cristiano Ronaldo has rejected an accusation that he raped an American woman in a Las Vegas hotel in 2009.

The Nevada woman has sued Ronaldo, 33, and is participating in a police investigation of the soccer star, according to a complaint filed by her lawyer.

Lawyers for Ronaldo, one of the world’s best-known athletes, on Friday threatened to sue a German magazine that published the accusation.

Kathryn Mayorga sued Ronaldo in a district court in Clark County, Nevada on Thursday, and is also seeking to void a $US375,000 ($520,000) settlement she alleges she was coerced into signing to keep quiet, according to the complaint seen by Reuters and according to Mayorga’s lawyer.

Ronaldo has declared the situation “fake news” and posted an Instagram video saying: “They want to promote [themselves] by [using] my name. It’s normal.”

Ronaldo, with his girlfriend Georgina Rodriguez and son Cristiano Jr at Kiev in May, says the report is “fake news”. Photo: Getty

On Monday, GestiFute – the company that manages Ronaldo – said it had no comment beyond a Friday statement by the Juventus striker’s lawyer Christian Schertz, who called the German magazine report “an inadmissible reporting of suspicions in the area of privacy”.

The lawsuit contends that Ronaldo met Ms Mayorga at a Las Vegas nightclub in June 2009 and the next night invited a group of people, including Ms Mayorga, back to the penthouse suite where he was staying.

That night, the lawsuit alleges, Ronaldo asked the woman to perform a sexual act on him in a bathroom as she was changing into attire to wear in a hot tub. He then pulled her into a bedroom and raped her as she screamed “no, no, no,” the lawsuit said.

“When Cristiano Ronaldo completed the sexual assault of the plaintiff, he allowed her to leave the bedroom stating he was sorry. He was usually a gentleman,” the lawsuit alleges.

The Las Vegas Metropolitan Police on Monday said an incident report with the number listed in Ms Mayorga’s lawsuit was filed on the night of the alleged attack, and said the case was reopened last month after the unidentified victim came forward with new information.

They declined to say whether the athlete was the subject of an investigation.

Lawyers for the Portuguese athlete said in a statement on Friday they would sue German magazine Der Spiegel after it published “blatantly illegal” accusations by Ms Mayorga.

They did not respond to specific questions about the content of the Der Spiegel report.

-AAP