Liverpool are investigating claims fans were subjected to violent policing and denied entry to Tuesday's Champions League draw away to Sevilla, reports BBC Sport.
Fans shared stories of policing on social media, with a female supporter claiming she was punched.
Liverpool said accounts from supporters were "detailed and troubling".
In a statement, Uefa said: "We are aware that there were some issues at the away supporters entrances in regards to fans accessing the stadium."
European football's governing body added it had no further comment to make at this stage.
Liverpool said they are "seeking to establish the facts" about fans' treatment "at the hands of the host stewards and local police force" at the Ramon Sanchez Pizjuan.
The club added: "The safety and security of our supporters is our paramount concern and we intend to gather all the relevant information before responding further."