Arsenal have condemned "unacceptable" racial abuse Jordi Osei-Tutu has said he suffered during a pre-season friendly for loan club VfL Bochum.
Osei-Tutu, 20, left the pitch in tears saying an opposition player had abused him.
The defender, who signed for second-tier German side Bochum on a season-long loan, started in the warm-up match with Swiss team St Gallen on Tuesday.
The incident occurred two minutes after Osei-Tutu was booked for a late tackle.
Arsenal have said they are "working closely with Bochum" and are giving the player their full support.
"Racism has no place in our game and we do not tolerate any form of discrimination," a club statement read.
Osei-Tutu shrugged off team-mates before being escorted away by a member of the Bochum coaching staff, but managed to compose himself before returning to the action.
In a statement, the defender, who is yet to make a senior appearance for Arsenal, said: "I am very disappointed about what happened.
"No one should ever be subject to any discrimination and it is really hard to understand how a fellow professional footballer could do this.
"Arsenal and Bochum have provided great support to me and I hope that, if nothing else, we can show that racism has no place within football."
St Gallen also condemned all forms of discrimination in the "strongest possible way".
"With our players from different countries and cultures, we are an example of mutual understanding and tolerance," they said in a statement.
"Our players take care of each other, completely regardless of origin, skin colour or religion. The player concerned, in a hearing with the people in charge, assured us that he had followed this association principle."