Newcastle have confirmed midfielder Sandro Tonali is being investigated by the Italian Prosecutor's Office and Italian Football Federation (FIGC) for breaching betting rules.
The 23-year-old Italy international was withdrawn from his country's Euro 2024 qualifying defeat to England at Wembley on Tuesday night and his club have released a statement to say he is co-operating with the investigation.
The Premier League club said: "Newcastle United can confirm that Sandro Tonali is subject to investigation by the Italian Prosecutor's Office and Italian Football Federation (FIGC) in relation to illegal betting activity.
"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.
"Due to this ongoing process, Sandro and Newcastle United are unable to offer further comment at this time."
Eddie Howe must decide whether to include Tonali in his Newcastle squad when they return to Premier League action against Crystal Palace on Saturday.
Tonali is free to play for the club while he awaits a verdict in his case and is training with his team-mates.
The midfielder admitted on Tuesday to making bets on Milan to win games, in a hearing at the Italian Federation in Turin.
Tonali was one of the players named in an Italian football betting probe last week, and was withdrawn from the senior men's squad for Tuesday's defeat against England.
Sky Sports News understands that at his hearing on Tuesday he admitted to betting on matches - both in which he played and did not play - for Milan to win.
According to FIFA Code 26, conduct such as this can see players face up to a three-year ban from worldwide football.
Tonali is likely to face a lesser, but still lengthy ban for his help with the investigation - and for admitting his guilt.
Sky Italy have reported that Tonali and his legal team are seeking a plea bargain to reduce his potential ban.
Juventus' Nicolo Fagioli banned for seven months over breach of betting rules
On Tuesday Juventus midfielder Nicolo Fagioli, the first player named in the probe, was served a seven-month ban for betting on football. He self-reported himself, while Tonali did not.
Fagioli had five months of a one-year ban suspended and was fined 12,500 euros (£10,848), while he agreed to a therapy plan of at least six months to tackle his gambling problem, the FIGC announced.
In a statement on its website, the governing body said the 22-year-old violated the rule "that prohibits betting on football events organised by FIGC, UEFA and FIFA".
On Tuesday, Tonali's agent admitted the player had a gambling problem and said he faces the biggest challenge of his career.
Roma offer support to Zalewski and El Shaarawy
Roma have offered their "full support" to Nicola Zalewski and Stephan El Shaarawy after they were subjected to "reputation-damaging speculation" amid the Italian betting investigation.
Both players have denied having any involvement. El Shaarawy was called up to the Italy squad for this month's Euro 2024 qualifiers after Tonali and Zaniolo withdrew for their involvement in the investigation.
"In response to recent rumours regarding the alleged involvement of some of the club's players in the football betting investigation, AS Roma expresses its full support for Nicola Zalewski and Stephan El Shaarawy, who have been subjected to reputation-damaging speculation," a statement read.
"The club has total confidence in Nicola and Stephan when they claim to have nothing to do with this matter.'"