Las Vegas police have reopened an investigation into an alleged sexual assault, following claims made by a woman against Cristiano Ronaldo.

Kathryn Mayorga has reportedly accused Ronaldo of raping her in a hotel in the city in 2009. German publication Der Spiegel reported the claims on Friday, prompting Ronaldo to dismiss the story as "fake news" in an Instagram video.

Las Vegas Metropolitan Police has now released a statement confirming a sexual assault case from 2009 has been reopened, although it did not name the victim or any suspects.

READ: Alisson disappointed not to face Ronaldo in Serie A

"The Las Vegas Metropolitan Police Department responded to a call of a sexual assault on June 13, 2009," read a statement released to Omnisport .

"At the time the report was taken, the victim did not provide detectives with the location of the incident or suspect description. A medical exam was conducted."

"As of September 2018, the case has been reopened and our detectives are following up on information being provided by the victim. This is an on-going investigation and no further details will be released at this time."

ALSO READ: Juventus 3 Young Boys 0: Dybala hits hat-trick as Ronaldo watches on

Ronaldo's legal team described Der Spiegel's report as "blatantly illegal" and confirmed that it will pursue action against the publication for "inadmissible reporting of suspicions in the area of privacy".

According to Der Spiegel, Mayorga first made a complaint of sexual assault in 2009 and subsequently reached an out-of-court settlement with Ronaldo. It is claimed by the magazine she was paid $375,000 as part of a privacy agreement, preventing her from going public with the allegations.

Ronaldo joined Juventus from Real Madrid in July in a €112million deal, after spending nine years with the Spanish giant.