Joseph Minala, the Lazio youth teamer, could take legal action following questions over his age.
The Cameroonian, 17, has slammed "unfair allegations" and closed his Twitter account since tweeters doubted the veracity of his date of birth.
Lazio have now threatened legal action against those who have questioned the legitimacy.
"We reserve the right to take action against those responsible for the protection of the good name of the company and the footballer," the club said in a statement.
Midfielder Manala, who denied telling an African website he was actually 41, added: "I have read the alleged statements posted on the website senego.net in which it says I confessed my real age which was different to what was stated in my [official] documents.
"They are false statements that have been attributed to me by people who do not know."
Several African footballers' ages have been questioned in the past since confusion surrounded Italia '90 World Cup star Roger Milla's date of birth.
Nigerians Taribo West, Nwankwo Kanu and Yakubu Aiyegbeni have all been accused of lying about their age.