Arsenal's Granit Xhaka has been interviewed under caution by police following an allegation he racially abused an airline staff member at Heathrow on Monday night.
Xhaka, 24, is believed to have been accompanying a friend who had visited him in London and was returning home.
The man is understood to have arrived late for his flight back to Germany and was not allowed to board.
It is at this point that the racial abuse is alleged to have occurred.
Arsenal have declined to comment other than to say it is a private matter that is now in the hands of the police.