Ronaldo's lawyer, Peter Christiansen, played down the significance of the warrant sent to authorities in Italy, telling AFP in a statement on Thursday it was standard procedure.

"Mr Ronaldo has always maintained, as he does today, that what occurred in Las Vegas in 2009 was consensual in nature, so it is not surprising that DNA would be present, nor that the police would make this very standard request as part of their investigation," the statement said.

A former American model, Kathryn Mayorga, 34, of Las Vegas, accused Ronaldo in a complaint filed last year in Nevada of raping her on June 13, 2009 just before he joined Real Madrid from Manchester United.

Ronaldo, 33, has vehemently denied the allegations and has been backed by his current club.

Mayorga alleges that the sportsman raped her at a Las Vegas hotel and she was reportedly paid $375,000 to keep quiet.

Ronaldo's lawyers have said that the non-disclosure agreement signed with the former model is "by no means a confession of guilt."

Mayorga's attorney has previously said that the model agreed to an out-of-court settlement to keep her name from going public but was inspired to speak out by the #MeToo movement.

She met Ronaldo at a Vegas nightclub, according to her complaint, and accompanied him and other people to his hotel suite where the alleged attack took place.

Mayorga's attorney could not immediately be reached for comment on Thursday.