Cristiano Ronaldo's mother believes an unspecified football "mafia" could prevent the Juventus forward from winning a sixth Ballon d'Or because of his nationality.

Speaking at an event in Portugal, Dolores Aveiro claimed conspiratorial forces are the reason her highly decorated son has not further embellished his long list of achievements.

The former Manchester United and Real Madrid star earned global fame and adulation for his performances in the Premier League and LaLiga but slipped to second in the 2018 Ballon d'Or rankings while midway through his first Serie A campaign.

In September, he finished third in the voting for the title of The Best FIFA Men's Player, behind Lionel Messi and Virgil van Dijk.

Fellow five-time Ballon d'Or winner Messi is the only other player to have claimed the prestigious award on more than three occasions.

"There is a mafia in football, that's the right word to describe it," Dolores Aveiro told Portuguese media.

"If you look at everything that's happened you will realise that it is because of the mafia.

"If Cristiano was Spanish or English, they would not do what they did to him, but since he is Portuguese and from Madeira, well, this happens."

Ronaldo, Juve's record signing, was named Serie A's Most Valuable Player at the end of the 2018-19 season and helped Portugal triumph in the Nations League.

The 34-year-old's mother expects those efforts will be enough for him to beat Barcelona captain Messi to a sixth Ballon d'Or when the 2019 winner is announced.

"I don't know if he will receive it, but I am confident and I think he deserves it," she said, despite fearing he will be the victim of bias.

"If we analyse what he did during the season, he deserves it."