Tonali joined Newcastle from AC Milan in July for a reported fee of 70 million euros, a record sum for an Italian player. Legal and sporting authorities are investigating the use of illegal betting platforms by football players in Italy.

"Newcastle United can confirm Sandro Tonali is subject to investigation by the Italian Prosecutor's Office and Italian Football Federation (FIGC) in relation to illegal betting activity," the club said in a statement.

"Sandro is fully engaging with the investigation and will continue to cooperate with all relevant authorities. He and his family will continue to receive the club's full support."

Juventus's Nicolo Fagioli received a seven-month ban as part of a settlement with the FIGC after breaching rules on betting on matches, on Tuesday. Fagioli is under investigation by prosecutors in Turin for allegedly betting on illegal websites.

As the investigation into Tonali is ongoing, Newcastle said they were unable to offer any further comment at this time.