The Juventus forward received a positive test result on Tuesday ahead of the national team’s Nations League clash with Sweden, forcing him into self-isolation for a period of at least 10 days.
However, the 35-year-old broke his isolation to return to Italy by private jet on Wednesday, with Juventus keen to get him back in the country to complete his isolation period before their Champions League clash with Lionel Messi’s Barcelona side later this month.
Under Italian regulations, those who test positive for coronavirus only need to quarantine for 10 days, while the rules in Portugal were set at 14 days at the times that Ronaldo tested positive for Covid-19 - though their isolation period has since been reduced to 10 days.
But Vincenzo Spadafora, the Italian sports minister, believes Ronaldo was wrong to return to Italy after testing positive for the virus, meaning he could face legal action.
Asked during a radio interview if Ronaldo may have broken health rules, Spadafora replied: "Yes, I think so, if there hadn't been any specific authorisation from the health authority."
Juventus are confident that Ronaldo did no wrong though, with club president Andrea Agnelli claiming that no rules had been broken.
"You must call the Ministry of Health and the Ministry of the Interior and have them explain what has been violated," Agnelli said during a news conference.
Juventus said on Wednesday that Ronaldo had returned on a medical flight "authorised by the competent health authorities".
Ronaldo played a friendly against Spain and a Nations League match against France before he tested positive and was forced to miss the 3-0 win over Sweden on Wednesday.