Liverpool football club launched an investigation into an incident in the Spanish city of Barcelona where Reds supporters were filmed racially abusing an Asian man who was pushed into a fountain.
In the video, which circulated widely on social media, a Liverpool supporter could be seen shoving the man into the water at the Placa Reial ahead of Wednesday's Champions League semi-final first leg at the Camp Nou.
A second man, also believed to be a Liverpool fan, could then be heard saying, "Mr Miyagi, san", when the elderly man tried to speak to the person who pushed him.
Mr Miyagi is a racial reference to the fictional karate master in the Karate Kid films from the 1980s.
Another video also showed a street seller being thrown into the water.
Liverpool FC said it will investigate the incidents and were seeking to identify those involved.
"Such behaviour is clearly totally unacceptable and will not be tolerated," the statement said.
"It would be inappropriate to comment further while the situation is ongoing other than to confirm the club will follow due process in any and all cases of this nature".
Kick It Out, an organisation that tries to combat racism in football, praised Liverpool for taking "swift action on this alleged racist incident".
Liverpool CEO Peter Moore also pleaded with Liverpool fans to behave, tweeting: "We proudly sing that we've conquered all of Europe. But let's treat this beautiful city with the respect that it deserves, and act in a manner that is befitting of LFC.
"By all means have a good time, but we are Liverpool, and as such, let's visit here with grace and humility."
His comments came after six Liverpool fans were arrested by local authorities on Tuesday on suspicion of public order offences.
Spanish newspaper Sport reported fans had thrown objects at police and nearly 3,000 cans of beer, which were to be sold around the busy square, had been confiscated.
Thousands of Liverpool fans arrived in Barcelona ahead of Wednesday's crucial game between the two sides.
Both clubs have won five European cups each, but Barcelona are riding high after winning their 26th La Liga title on the weekend.
