An attack on a taxi carrying referees after a game in Athens has been condemned as "cowardly and criminal" by Euroleague Basketball.
Two people smashed the taxi window as the three match officials were being driven to a hotel after Friday's game between Panathinaikos and Barcelona.
The league said the attack was "unprecedented" in its 20-year history.
It warned that it would consider moving matches from Greece if another similar incident happened in the country.
"Two individuals performed a cowardly criminal attack," Euroleague said in a statement. "Fortunately, all three referees, the referee coach and the taxi driver are OK."
The league contacted police, who opened an investigation and "guaranteed the safety and security of the referees until they departed from Greece", the statement continued.
"Euroleague Basketball and all participating clubs condemn violent acts of any shape or form, and will continue to apply a zero-tolerance policy."
Barcelona won the match 92-81 at the Olympic Indoor Hall.
Euroleague Basketball said the perpetrators would be given life bans if indentified.
"Euroleague Basketball will seek the co-operation of the clubs and the local authorities to prevent any such incidents in the future," the league added.
"While the attack is unprecedented in the 20-season history of Euroleague Basketball, should a similar incident occur again within the territory of Greece, this would signify that a safe and secure environment for the visiting teams, referees and all other accredited personnel cannot be guaranteed.
"Therefore, Euroleague Basketball will immediately evaluate relocating all further Euroleague, EuroCup and Under-18 Tournament games outside of Greece."