The Sheffield-born England defender, who grew up in Mosborough and went to school in Chesterfield, is reported to have been involved in an alleged disturbance on the island of Mykonos on Thursday, August 20.
Manchester United have said they are aware of the incident involving their star centre back.
In a statement the club said: “The club is aware of an alleged incident involving Harry Maguire in Mykonos.
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“Contact has been made with Harry, and he is fully co-operating with the Greek authorities.
“At this time we will be making no further comment.”
National newspapers have reported his release from court and repeated claims from Greek news website Mykonos Voice that his sister Daisy was stabbed in the arm during the incident.
He pleaded not guilty in court but the exact charges are not clear.