The Italian Federation confirmed in a statement that Tonali and Zaniolo had left the squad ahead of games against Malta and England.

Italian news agency ANSA reported that both players had been questioned as part of a betting probe.

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The FIGC did not specify what the investigation was about, but said the two midfielders were allowed to go home as the federation believed they were not in the right state to face upcoming matches.

The players were notified of the probe by Turin prosecutors while at the national team's training centre in Coverciano.

A statement from the Italian Federation issued on Thursday read: "The Federation announces that this afternoon the Turin Public Prosecutor's Office has conducted investigations into players, Sandro Tonali and Nicolo Zaniolo, who are currently training with the national team at the Coverciano Federal Training Centre.

"Regardless of the nature of the events, considering that the two players are not in the necessary condition to face the matches scheduled for the next few days, the Federation has decided, also for their protection, to allow them to return to their respective clubs."

Italy host Malta on Saturday and then take on England at Wembley on Tuesday in European Championship qualifying.

Tonali, 23, joined Newcastle from AC Milan in July, while Aston Villa signed Zaniolo, 24, on loan from Turkey's Galasataray in August.

Sky Sports News has contacted Newcastle and Aston Villa.