Manchester United say captain Harry Maguire is "fully co-operating with the Greek authorities" following an "alleged incident" on the island of Mykonos on Thursday night.
Local reports have named Maguire as being involved in an incident, but no details have yet been comfirmed.
The England defender, 27, has been transferred from Mykonos to Syros in a police vehicle on a ship after reportedly being arrested following the alleged incident.
Police in Greece are continuing their investigation into the matter.
The England defender, 27, is on holiday in Greece.
He joined United from Leicester for £80m - a world record fee for a defender - in August 2019.
"The club is aware of an alleged incident involving Harry Maguire in Mykonos last night," United said in a statement on Friday.
"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."
